
HART ttisd TOTTINGHAM 




Gop^htl^". 



COPYRIGHT DEPOSIT. 



GENERAL 
AGRICULTURAL CHEMISTRY 



BY 

EDWIN B. HART 

Professor of Agricultural Chemistry in the 
Universiti/ of Wisconsin. 

AND 

WILLIAM E. TOTTINGHAM 

Assistant Professor of Agricultvral Chemistry in the 
University of \l'isconsin 



MADISON, WISCONSIN 
1910. 



4«1^ 



f 



COI'VRIGHT 1910 
15Y 

P:I)\VIN K. hart and WILLIAM E.TOTTIXGHAM. 



STATE JOUKNAI. PRINTING COMPANY 

Pkinters and Sterkotypers 

Madisos, Wts. 



€)CI.A:a7o972 



CK 



CONTENTS. 

I Introduction 7 

II The Atmosphere 23 

III The Soil o5 

IV Natural Waters 08 

V The Plant 79 

VI Farm Manure Ill 

VII Commercial Fertilizers 146 

VIII Crops 173 

IX The Animal Body 206 

X Feeding Standards 229 

XI Food Requirements of Animals 248 

XII Milk and its Products 205 

XIII Insecticides and Related Substances 294 

Appendix 315 

Index 327 



PREFACE 

Since the time of Liebig, agriculture in its many phases has 
profited from the science of chemistry, A store of useful infor- 
mation has been made available through the study of the elements 
and compounds fundamentally concerned in the art of agricul- 
ture. It is reasonable to expect that this art will in the future 
be enriched from the same source. 

This little book was written in the interest of the young farmer 
and the student beginning the study of agricultural chemistry. 
No extended knowledge of chemistry is required for its under- 
standing. It makes no special appeal to the chemist. It is a 
survey of the general field of chemistry applied to agriculture, 
with the emphasis always placed on the applied side. 

Throughout the book we have striven to express safe views 
rather than to echo the most recent. Hypotheses and theories 
have not been discussed. We have attempted to give, in general, 
only well tested and established principles. Formulas and re- 
cipes have been avoided as far as possible. While we recognize 
their helpfulness, nevertheless, they are as yet but imperfect 
expressions of relations not fully understood. 

The authors have drawn freely from various publications, en- 
deavoring to bring together from scattered sources the materials 
essential to such a work on agricultural chemistry. In this re- 
gard we are especially indebted to the works of Ingle, Warington, 
Storer, Voorhees, Vivian, Jordan and others, all of which have 
aided greatly in the preparation of this work. 



CHAPTER I. 
INTRODUCTION 

Agricultural chemistry concerns itself with the chemical com- 
position of the food of plants and animals and with the chemical 
changes involved in the processes of life. It has to deal with the 
composition of soil, air, and water, of the bodies of plants and 
animals, of manures and commercial fertilizers and with the 
chemical changes which these substances undergo. 

Before beginning the study of the soil or air or the plant it 
will be necessary for the student to learn something of the im- 
portant elements concerned in agriculture and the meaning of 
some of the common terms used in chemistry. 

The whole earth, so far as is known, is made up of about 
eighty-one elements, a large proportion of which play little or 
no part in the ordinary processes of plant and animal life. In- 
deed a considerable proportion are found only in extremely small 
quantities and are but curiosities to the student of chemistry. 
Prom the standpoint of the farmer they possess no interest. They 
are called elements for the reason that they are the simplest sub- 
stances known, and cannot by any means yet discovered, be sep- 
arated into simpler or different substances. Iron, gold, silver, 
zinc, lead, and sulphur are examples of elements. 

The bodies of plants and animals are built up of compounds 
of the following elements and these, therefore, become of the 
first importance to the farmer: 

Oxygen Phosphorus Sodium 

Hydrogen Calcium Iron 

Carbon Magnesium Chlorine 

Nitrogen Potassium Silicon 
Sulphur 

A short account of these elements will be given at this place. 
Oxygen (0) is the most abundant and most important of the 
elements. It forms about half the weight of the solid crust of 



8 Agriculiwal Chemistry, 

the earth, eight-ninths of the water, and about one-fifth of the 
weight of the air. In the first and second instances the oxygen 
is in a combined state. That which is held in chemical combina- 
tion in the soil takes no part in the formation of plant tissue. 
In the atmosphere it exists as a free element, merely mixed Avitb 
the other constituents. Oxygen in the interstices of the soil is 
an active agent in bringing about many chemical changes, as 
oxidation of the organic matter and disintegration of the soil 
particles. It also forms about fifty per cent of the compounds 
found in plants and animals. 

Oxygen is a colorless, odorless gas and veiy slightly soluble in 
water. It shows great tendency to combine with other substances 
and the act of union is usually attended by the production of 
much heat. liurning or combustion is nearly always due to the 
heat produced by the combination of the substance burned with 
the oxygen of the air. Any substance, which will burn in air 
(containing about twenty-one per cent of free oxygen) will bum 
with increased brilliancy in pure oxygen. 

It is possible, with suitable apparatus, to measure the quantity 
of heat a substance will produce Avhen burned. The vmit of heat 
here employed is the "calorie," which represents the quantity 
of heat required to raise one gram (about 1-28 of an ounce) of 
water from 0° to 1° on the scale of the centigrade thermometer. 
A large Calorie, one thousand times larger than the above, is 
employed for the expression of large quantities of heat and will 
be employed here. 

Wben one gram of the following dry substances is burned in 
oxygen, the quantity of heat produced, expressed in large Cal- 
ories, is as follows : 



Charcoal «.0 

Hydrogen 34 . 4 

Wood 2.8 

Coal 7.5 

Coke 7.0 

Casein 5.8 



Fat of sheei> !».4 

Fat of butter 9.2 

Cane sugar 4.0 

Cellulose 4.1 

Starch 4.1 



Jnlrod'uction. 9 

In ordinary cases of burning, the evolution of heat is readily 
evident, but in some cases the combustion is so slow that the 
heat evolved is carried away as fast as produced and very slight 
or no elevation of temperature is apparent. In some cases of 
slow combustion where the escape of heat is hindered from any 
cause, the temperature may rise so as to be perceptible or even 
dangerous. It may, under particularly favorable conditions, rise 
sufficiently to start a rapid combustion with oxygen and flames 
then result. Such cases of '^spontaneous combustion" frequently 
occur. Drying oils, as linseed or cotton-seed oil, especially when 
spread on cotton waste, and fermentation changes in vegetable 
matter as hay and tobacco are notable examples of these condi- 
tions. 

Hydrogen (II). This element is rarely found in a free state 
in nature, but is combined with carbon and ox^^gen as in animal 
and vegetable matter, with oxygen to fonn water, and in a few 
cases with some of the base elements to form hydroxides. It is 
not found in large amounts in the soil and that which forms a 
part of the tissues of plants and animals comes largely from the 
hydrogen in water. It is a colorless, odorless gas and charac- 
terized by its lightness. This fact has led to its use for filling 
balloons, although coal gas is now more generally employed but 
is not nearly so efficient. In a free state it has been found in 
the gases escaping from volcanoes. 

Carbon (C) is the element most closely associated A\ath plant 
and animal life. It forms a large proportion of the solid matter 
of all living beings; and the chemical processes of animal and 
plant life are mainly those in which carbon plaj^s an important 
part. It exists in the combined state in many minerals as the 
carbonates of calcimn, magnesium, iron, zinc, and also in a small 
but very important constituent of the air, carbon dioxide. The 
carbon of the soil, M'here it exists as the main constituent of 
organic bodies, takes no direct part in forming the carbon cora- 
];ounds of the plant. It is not necessary to apply carbon fer- 



]0 AgncnUvral Chemistry. 

tilizers to produce the carbon compounds of the plant, because 
the carbon dioxide of the air is the source for crop production. 
It is estimated that there arc about thirty tons of carbon dioxide 
in the air over every acre of the earth's surface. 

This element occurs in three distinct forms: (1) as the 
diamond, (2) as graphite and (3) as charcoal, lamp black, etc. 
The diamond is crystalline and transparent; graphite is crv'stal- 
line but opaque; while lamp black and charcoal are non-crystal- 
line. The black carbon which is produced when animal or vege- 
table substances are strongly heated without access of air (char- 
ring) is due to the separation of free carbon from the various car- 
bonaceous compounds present. 

Nitrogen (N) is much less abundant in nature than the ele- 
ments already described. A peculiarity of its occurrence is that 
it appears to be present only in the outermost portion of the earth, 
the greater portion being free in the air. No true minerals con- 
taining it are known except those which owe their origin directly 
to plant or animal life, as coal, and Chili salt-petre. All living 
matter, however, contains it as an essential constituent. In its 
free state it is a colorless, odorless gas, showing little tendency to 
combine with other elements. It constitutes about seventy-nine 
per cent of the atmosphere and over each acre of land there is 
consequently about thirty thousand tons. 

Although in the free state it is so inert, the nitrogen compounds, 
as a rule, possess great chemical activity and many are very im- 
portant substances. Some powerful drugs and poisons as quin- 
ine, strychnine, and prussic acid contain nitrogen, while most ex- 
plosives, as nitro-glycerine and gun cotton are also nitrogen com- 
pounds. It is an absolutely essential ingredient in the food of 
hotli animals and plants. It must be supplied to animals in com- 
pounds in which it is combined with carbon, hydrogen, oxygen, 
and certain other elements and which are known as proteins. 
while phmts acquire it generally from nitrates, which are simple 
compounds of oxygen, nitrogen, and some base, as calcium, so- 
idum, and j)ota.ssium. Only under very special conditions can 



Introduction. 11 

some species of plants obtain their necessary nitrogen from the 
air. It will be seen in the later chapters that, although plants 
are surrounded by air, rich in free nitrogen, combined nitrogen 
is one of the essential and most valuable constituents of manures. 
A large part of the nitrogen in the food consumed by man and 
animals is eliminated as simple compounds in the excreta and un- 
fortunately, especially in our cities, sent down the sewers and 
rivers and finally discharged into the sea. To agriculture this 
valuable combined nitrogen is therefore wasted. This element is 
the most expensive of those necessary for plant growth and is 
among those liable to be most deficient in our soils. No other ele- 
ment takes such an important part in agriculture or in life pro- 
cesses. 

Sulphur (S) is found both free and combined in nature. The 
free element is found in volcanic districts, while in the combined 
state it occurs as hydrogen sulphide in mineral waters and as sul- 
phides of many metals, as for example iron, lead, and zinc. The 
sulphide of iron, known as iron pyrites, is often mistaken for gold 
because of its yellow color ; sulphur also occurs as sulphate of cal- 
cium, in which form it is very widely distributed in soils, and is 
the main source of the sulphur for crops. 

The element sulphur (brimstone) is a yellow, brittle substance 
and very inflammable. It bums in air -with a pale blue flame, 
forming the suffocating gas, sulphur dioxide. Such forms of sul- 
phur are very poisonous to plants and animals, while sulphates 
are not only harmless, but necessary. Sulphur is present in the 
proteins of both plants and animals and when putrefaction of 
these substances occurs is often liberated as hydrogen sulphide. 
This substance is perceptible by its disagreeable odor as one of 
the chief products of the decay of eggs. 

There is generally less than 0.10 per cent of sulphur trioxide. 
as sulphates in ordinary soil, and it is now known that the amount 
required by crops is considerable ; for this reason it may be neces- 
sary to use certain sulphates occasionally as fertilizers and as 
sources of sulphur for the growing crops. 



12 Agricultural Chemistry. 

Phosphorus (P) always occurs in a state of combination. 
Phosphorus compounds, chiefly phosphates, are very widely dis- 
tributed, but in small proportion, in the rocks of the earth. De- 
posits of calcium phosphate occur in certain localities and are 
one of the chief sources of our phosphate fertilizers. All fertile 
soils contain small quantities of phosphates, which are taken up 
by plants and through plants find their way into animals, where 
they accumulate in the bones or other hard parts, as teeth and 
shells. 

The element phosphorus, as usually prepared, is a yellowish 
waxy substance, Avhich has the power of emitting a faint light 
when exposed to the air. This property was the origin of its 
name, Avhich is derived from the Greek and means "the light 
bearer." The emission of light is due to slow combination with 
the oxygen of the air, resulting in the production of heat. 

Phosphorus is a violent poison. -It is largely used in the man- 
ufacture of lucifer matches and rat-poison. For the farmer its 
chief importance lies in the use of its compounds, the phosphates, 
as fertilizers, and its occurrence in certain fats and protein com- 
pounds of feeding stuffs and in the bodies of animals. 

Soils are quite liable to be deficient in phosphates, as the latter 
are largely drawn upon by many crops, particularly grain crops, 
where the phosphorus accumulates in the seed and is sold from 
the farm. 

Calcium (Ca) is veiy abundant in nature, always occurring in 
a combined state. Calcium carbonate is found in enormous quan- 
tities, as chalk, limestone and marble, and contains the three ele- 
ments, calcium, carbon and oxygen. It also occurs as gypsum, a 
compound of calcium, sulphur and oxj-gen. The element itself 
is an easily oxidisable metal, difiicult to prepare, and of no im- 
portfince to the fanlier. Its oxide, or a compound of calcium and 
oxygen, is the important substance, quick lime. This is made by 
burning limestone, whereby the carbon and part of the oxygen 
are removed as a gas. Calcium is an essential constituent of 



^ 



Introduction. 13 

plant food and in the soil is present in a variety of forms, as 
calcium carbonate, calcium sulphate and calcium phosphate. 

Potassium (K) occurs in many minerals. It will be found in 
many silicates, as orthoclase or mica, which are complex com- 
pounds of potassium, silicon, aluminum, oxygen and other ele- 
ments. It also occurs in sea water, from which sea weeds accu- 
mulate large quantities of potassium compounds. The immense 
salt deposits at Stassfurth, Germany, furnish a large proportion 
of the potassium used in our potash fertilizers. 

The element is a lustrous metal, very soft, and so susceptible to 
change in the air that it must be kept away from contact with 
air or moisture by immersion in naphtha. By contact with water 
it reacts violently, producing much heat and floating on the sur- 
face of the water with a hissing sound. 

Potassium compounds are of the greatest importance in agri- 
culture and are necessary constituents of all fertile soils. They 
are intimately associated with the growth and increase of plants 
and are always found in greatest abundance in the twigs, young 
leaves and other rapidly growing portions. In some plants the 
potassium is in combination with certain organic acids, as citric 
and tartaric acids. In the ash of plants — that which is left after 
burning — it generally occurs as a carbonate. Potassium salts are 
very soluble in water, but are absorbed and retained by certain 
constituents of the soil, so that their loss by drainage from soil 
is little to be feared. 

Sodium (Na) is very widely distributed in nature and is a con- 
stituent of many silicates. In the form of sodium chloride — a 
compound of sodium and chlorine — it is very plentiful as rock 
salt and as the largest saline constituent of sea-water. 

Its properties resemble those of potassium. Sodium compounds 
are largely used in the arts and the preparation of sodium car- 
bonate is one of the largest and most important of chemical in- 
dustries. 

Sodium is found in the ash of most plants, but, except in the 



14 Agricultural Chemistry. 

case of certain plants, does not appear to be essential to their 
development. A striking difference between sodium and potas- 
sium compounds, which are so much alike in most of their proper- 
ties, is in their behavior towards the soil when applied in solution. 
The potassium salts are retained by the clay and organic matter 
in an insoluble form, but the sodium salts are more easily washed 
out by water and escape into the drains. Although like potassium 
in its chemical properties it cannot take its place in agriculture. 

Magnesium (Mg) is widely met in nature as carbonate and 
silicate. The element itself is a bright, §ilvery metal, and capable 
of burning in air with an intense and dazzling white light. IMag- 
nesium is found in the ash of plants and is required by all crops. 
It is particularly abundant in the seeds. There is generally in 
all soils an amount sufficient for crop purposes and it is not 
necessary to consider this element in connection with fertilizers. 

Iron (Fe) occurs in a large number of compounds. Haematite, 
a compound of iron and oxygen, magnetite, a similar com- 
pound, but Avith a different proportion of oxygen, and spathic 
iron ore, a compoimd of iron, carbon, and oxygen; the above are 
all abundant minerals and valued as ores of iron. The element 
occurs in two states of combination with oxygen, one a relatively 
small gmount and called ferrous iron, the other a relatively larger 
amount and designated ferric iron. The former yields salts which 
are white or green in color, while those of the latter are red or 
yellow. Ferrous compounds are often present in rocks or min- 
erals deep under ground, but when brought to the surface they 
combine with the oxygen of the air to form ferric compounds. 
The change of the state of iron is indicated by a change in color, 
often from green or gray to red or yellow. Only ferric com- 
poimds should exist in good soils. Iron is essential to plants, but 
a small quantity is all that is required and most soils contain 
from one to four per cent, an abundant supply. 

Chlorine (CI) is very abundant, especially in combination with 
sodium, as rock salt in the sea and in spring water. Other com- 
pounds of chlorine also occur as minerals. The element chlorine 



Introduction. 15 

is a yellowish green gas with an irritating and suffocating smell, 
very soluble in water and of great chemical activity. The prop- 
erties of chlorine, which are most valued in the arts, are its 
bleaching, disinfecting and deodorizing powers. It readily de- 
stroys most coloring matters and is largely employed in bleaching 
vegetable textile fabrics, as cotton or linen. It cannot be used for 
woolen or silk fabrics, as it injures the fibres themselves. Chlor- 
ine only bleaches in the presence of water and it really acts by 
decomposing the water, with formation of oxygen, which is the 
active agent. Its action as a disinfectant is probably due to the 
same process, the oxygen of the water combining with the or- 
ganic matter and micro-organisms and destroying them. 

Chlorine is present in all soils, generally in combination with 
sodium, as sodium chloride. It is present in all plants, although 
its necessity for plant growth may be questioned. Crops have 
been brought to maturity in its entire absence. Chlorine with 
sodium, as common salt, is sometimes used as an indirect fertilzer. 

Silicon (Si) is extremely abundant in the rocks of the earth's 
crust, and though it forms a very important ingredient in soils 
and occurs in most plant ashes, it does not appear to be abso- 
lutely essential as a plant food. Some recent work, however, has 
shown that soluble silica in a soil enables a plant to subsist in the 
presence of a smaller quantity of phosphoric acid than would be 
necessary without the silica. 

The element itself is a bro\\Ti solid and at one time was difficult 
to prepare in any quantity. At present, with the electric fur- 
nace, it is easily produced and its price per pound has been 
greatly reduced. 

The oxide, called silica, is a compound of silicon and oxygen 
and is a very abundant substance, occurring free as quartz, flint 
and sand ; in combination with metals the very numerous and im- 
portant substances called silicates, are produced. It has been 
estimated that nearly half of the solid mass of the earth's crust 
consists of silica. 



IG Agricultural Chemistry. 

DEFINITIONS. 

It now becomes necessary to define, in a fragmentary way, 
some of the commoner terms used in chemistry. 

Acid. A substance generally possessing a sour taste and the 
property of changing vegetable blues, as blue litmus, to red. As 
types of acids, we have sulphuric acid, commonly used for the 
Babcock test, and acetic acid, the principal acid in vinegar. The 
possession of a sour taste and the power of changing vegetable 
blues to red is indicated by saying that the substance has an acid 
reaction. 

Alkali. A substance opposed in its properties to an acid, cap- 
able of neutralizing and destroying the characteristics of an acid, 
forming in so doing, a salt. The most important alkalies are 
soda, potash, lime, and ammonia. A substance is said to have an 
alkaline reaction if it turns certain vegetable colors, as red litmus, 
to a blue color. 

Organic matter, strictly speaking, is matter which has been 
produced by organisms, such as plants or animals, but the term 
is used in a wider sense in chemistry for any compound of carbon, 
whether produced by life processes or artificially. Almost all 
fonns of organic matter, when strongly heated out of contact with 
air, blacken, owing to the liberation of carbon. With free access 
of air, combustion occurs, and carbon dioxide and other products 
are formed. 

Oxidation and Reduction. By oxidation, literally speaking, 
is meant union with oxygen, but in a chemical sense the term is 
given a wider significance, that is, combination with more oxygen 
or with some sulistance playing the part of oxygen. 

Reduction is used in exactly the opposite sense. A substance 
which brings about oxidation, is called an ''oxidizing agent" 
while one Avhich removes oxygen is called a "reducing agent." 
Common oxidizing agents are air, nitric acid, nitrates and chlor- 
ine ; common reducing agents are easily oxidizable metals, as zinc, 
and many forms of decaying organic matter. 



Inb^odudlon. 17 

Fermentation. A process of decomposition, often accompan- 
ied by the oxidation of carbonaceous matter, and produced by the 
life processes of bacteria, yeasts and molds. When the process 
occurs out of free access of air and bad smelling gases are formed, 
the process is called puirefaciion. 

The constituents of plants. All agriculture depends upon the 
growth of plants and consequently all profit for the farmer de- 
pends upon the value of the crop his farm produces. This is 
true whether the crop is sold directly from the farm or whether 
it is fed to animals and the products such as live stock, beef, pork, 
wool, eggs, or milk, used as the source of revenue. If the crops 
now produced on two hundred acres of land could be grown on 
one hundred without a great increase of labor and other expense, 
the profit would be greater. Successful farmers have demon- 
strated that the present average of crops can be doubled, and that 
at a cost per acre scarceh' more than is now required for the one- 
half crop. 

To accomplish this requires a broader knowledge of the food 
requirements of plants than is possessed by most of our farmers. 
A thorough understanding of the subject of plant food and plant 
nutrition by our forerunners in agriculture would have rendered 
it unnecessary to emphasize constantly the relation of the con- 
stituents of the plant to soil exhaustion. 

It is common experience that continued cropping results in a 
loss of fertility. The productiveness of a virgin soil seems un- 
limited, for large crops are produced from year to year with no 
apparent decrease. But sooner or later they begin to diminish 
in size, gradually to be sure, but unceasingly, until at last the 
yield becomes so small as to make the cost and labor of produc- 
tion unprofitable. 

At the Experiment Station at Rothamsted, England, barley 
grown continuously on the same plot for forty-three years with- 
out the use of fertilizers of any kind, yielded in the forty-third 
year 10 bushels of dressed grain per acre, the average for the 
laijt eight years being 11% bushels. Wheat grown for fifty years 



18 Agricultural Chemistry. 



I 



in the same way produced in the fiftieth year 9% bushels of grain 
per acre, the average for the last eight years being IIV2 bushels. 
The soil seems capable of keeping up the yield indefinitely, but 
the amount of crop produced ceases to be profitable. 

It is evident that the virgin soil must have contained largo 
amounts of some substances that were necessary for vigorous 
plant growth and that these were removed by the successive crops 
when harvested. The rapid decrease in fertility finds its most 
rational explanation on this basis. Changes in climate and phy- 
sical condition of the soil are inadequate as explanations for this 
decreased productive power. 

A description of the elements important to agriculture has al- 
ready been given and the very reason for their importance to the 
farmer lies in the fact that they are the elements which constitute 
the compounds of plants and are removed from the soil when the 
crop is hai*vested. 

Source of elements. However, not all of the elements de- 
scribed have come from the soil. Plants obtain the elements of 
which they are built up partly from the soil and partly from the 
atmosphere. From the soil they obtain by means of their roots 
all their ash constituents, all their sulphur and phosphorus, and 
in most cases, nearly the whole of their nitrogen and water. From 
the atmosphere they obtain, through the instrumentality of their 
leaves, the whole or nearly the whole, of their carbon. There are 
exceptions, especially in regard to nitrogen, which is obtained 
from the atmosphere by certain plants, such as alfalfa, clover, 
vetch, pea and bean, under certain conditions to be described 
later. 

Composition of the plant. The most abundant ingredient of 
a living plant is water. Many succulent vegetables, as the turnip 
and lettuce contain more than ninety per cent of water. The 
green com plant contains eighty-five to ninety per cent of water. 

Combustible part of plants. If a stalk of com is dried and 
burned the greater part is consumed and passes away in the form 
of gas. But there is always left behind a small quantity of white 



IntroducUon. 19 

ash, coiTespondiug exactly to the ash left in the stove after a stick 
of timber is burned. 

The constituents which form the dry matter of plants may be 
divided into two classes — the conibustihle and the non-cornbustible 
part. The combustible part of plants is made up of six chemical 
elements — carbon, oxygen, hydrogen, nitrogen and sulphur, with 
a small amount of phosphorus. Without these no plant will grow. 
Carbon generally forms about one-half of the dry combustible 
part of plants. Nitrogen seldom exceeds four per cent of the dry 
matter and is generally present in much smaller amounts. Sul- 
phur and phasphorus are still smaller in quantity. The re- 
mainder is made up of oxygen and hydrogen. The carbon, hy- 
drogen and oxygen form the cellulose, starch, lignin, gummy mat- 
ters, sugars, fats and vegetable acids which plants contain. The 
same elements united -with sulphur and nitrogen form the very 
important proteins, which are the life centers of the plant. "When 
all the above elements are united to phosphorus, we have addi- 
tional important groups of plant compounds, called nucleins and 
lecithins. 

Non-combustible part of plants. The non-combustible or ash 
constituents form generally but a small part of the plant. A 
fresh, mature corn plant will contain about 1.2 per cent of ash, 
while the corn grain when dry, contains about 1.5 per cent. In 
the straw of cereals the ash constitutes 4-7 per cent and cereal 
grains 2-3 per cent of the dry matter. In hay 5-9 per cent will 
be found. We find in leaves, especially old leaves, the greatest 
proportion of ash. In the leaves of root crops the ash will amount 
to 10-25 per cent of the dry matter. 

Essential elements. The non-combustible ash always contains 
six elements — potassium, magnesium, calcium, iron, phosphorus 
and sulphur. It was once thought that these ash elements were 
accidental, simply dissolved in the soil water and absorbed by the 
plant and that they were not essential to its development. Liebig 
proved that they were necessary; seeds were planted in pure 
quartz sand contained in a series of pots to one of which nitrogen 



20 



Agricultural Chemistry. 



(ioinpoimds alone were added, and to the others, nitrogen com- 
ponnds phis a small amount of plant ash. The plants in the pots 
which received the ash grew to maturity, while those in the other 
pots made only a feeble growth. 




4 3 12 5 

Water cultures of buckwheat. This method of experimental culture, 
"Which is known as water culture, has been of the greatest service 
in determining which elements are essential for plant growth. 
No. 1. Plant grown in normal solution. 
No. 2. Plant grown in normal solution without potassium. 
No. 3. Plant grown in normal solution with sodium instead of 

potassium. 
No. 4. Plant grown in normal solution without calcium. 
No. 5. Plant grown in normal solution without nitrogen. 

Non-essential elements. Besides the elements just named an 
ash will generally contain sodium, silicon, chlorine, and frequent- 
ly manganese, and perhaps minute traces of other elements. 
These elements just named sometimes form a considerable portion 



Introduction. 21 

of the ash. For the reason that plants have been brought to 
maturity in their absence, it has been generally accepted that they 
are non-essential. However, it is necessary to remember that 
such experiments have generally extended over a single genera- 
tion and that it is possible that an attempt to grow the crop 
through successive generations from its own seed in a soil devoid 
of sodium, chlorine, silica, or manganese might meet with failure. 

How ash elements occur. The ash elements named above oc- 
cur in part in the plant as salts, being combined with phosphoric, 
nitric, sulphuric and various vegetable acids of which acetic, 
oxalic, malic, tartaric and citric acids are the most common. It 
is also very certain that part is in combination with the organic 
or combustible part of the plant. Sulphur occurs partly as sul- 
phates and also as a constituent of proteins. Phosphorus as a 
phosphate in the stem and root of the plant, but in organic form 
in its seeds. In addition, such ash elements as potassium, mag- 
nesium, calcium, iron and silicon are very probably in part con- 
stituents of the organic compounds of plants. 

It is usual to speak of the combustible ingredients of a plant 
as organic, and of the non-combustible ingredients as inorganic. 
This is not accurate, as these ash constituents, which are essential 
for the growth of the plant, have during its life as much right 
to be called organic as the carbon of starch or protein. 

Can one element displace another? The fact that some of the 
elements found in plant ash, as sodium and potassium, are chem- 
ically very much alike, has led to the attempt to displace the ex- 
pensive and less commonly occurring potassium by the inexpen- 
sive and relatively abundant element, sodium. If it were pos- 
sible to do this, the farmer's fertilizer bills for potassium salts 
would be materially reduced. However, experiments have dem- 
onstrated that sodium cannot take the place of potassium in the 
growth of the plant. 

A definite amount of all the essential elements is needed for a 
certain yield and none of the elements can be replaced by another'. 
A crop will be limited by the quantity of the essential element 



22 



.'1 gricuUural Chemistry. 



present in least quantity compared with the requirements of that 
crop. If a field of corn can obtain only potash enough for a half 
crop, no more than this can be produced, no matter how much of 
the other forms of plant food is present. 

The following table shows the ingredients, expressed as pounds, 
in 1000 lbs. of the matured com plant, when the plant is to be 
cut for shocking : 

f \ Hydrogen ... 88.1 

Water \ 

[Oxygen 704.9 



1000 lbs. 



Water 
793 



f Organic matter 
I 195 



Corn Plants Dry matter -{ 



207 



Ash 12 



f Protein 18 

jFat 5 

I Fibre 50 "j 

[Carbohydrates.. 122 

r Chlorine 0.4 

I Potash 4.0 

1.2 
1.6 
1.4 
0.3 
0..3 
0.4 
2.4 



f Nitrogen 2.9 

I Carbon 90.5 

j Oxygen 88.9 

[Hydrogen 12.7 



I Phosphoric acid. 

j Lime 

1 Magnesia 

Iron oxide 

' Sulphur trioxide. 

I Soda 

[Silica 



All the elements mentioned above as occurring in the ash, with 
the exception of chlorine, are combined with oxygen. In the 
table the names under "ash" represent these combinations: pot- 
ash is composed of potassium and oxygen; phosphoric acid of 
phosphorus and oxygen; lime of calcium and oxygen; sulphur 
trioxide of sulphur and oxygen. 

The table shows that three elements, hydrogen, oxygen and car- 
bon, make up 981/0 per cent of the entire composition of the plant, 
the remaining elements constituting only ] l^ per cent. 



CHAPTER II 
THE ATMOSPHERE 

The atmosphere or air forms an invisible envelope surrounding 
and resting upon the earth. It's exact thickness is unknown, for 
it blends gradually with the imperceptible ether which fills inter- 
planetary space. While its functions are less apparent than 
those of water and soil, it nevertheless bears important relations 
to agricultural life and industries. 

Weight of the air. The resistance which air offers to rapidly 
moving bodies, its own motion as wind and the support of clouds 
and other bodies are evidences of its mass. The pressure by 
which it forces water into the vacuum of a pump or balances a 
column of mercury in the barometer is a measure of its weight, 
which is approximately 15 pounds per square inch at sea level, 
or 41,300 tons for each acre of the earth's surface. Were the air 
of uniform density throughout, its height could be easily meas- 
ured. The barometer falls, however, with decreasing rapidity as 
it is raised from the earth, thus proving that the air decreases 
in density vsdth increase in height. 

Height of the air. The band of haze attending the earth's 
shadow at lunar eclipse, the twilight period upon the earth, the 
time of falling meteors and other phenomena dependent upon the 
atmosphere give means of estimating its approximate height as 
at least 200 miles. 

Air essential to life. If an animal be enclosed ^vith a supply 
of food in a perfectly tight chamber but with a limited supply of 
air it >vill finally suffocate. This occurs as a result of exhausting 
the greater part of a constituent of the air known as oxygen. 
This element is absolutely essential to the processes by which food 
is assimilated and waste matter is expelled from the animal body. 
So too, if a plant be similarly enclosed, it will finally cease to grow 
and prematurely die. This is because it exhausts the limited sup- 



24 AgHcultural Chemisti^. 

ply of carbon dioxide, a constituent of the air, which is the basal 
material for all compounds made by the growing plant. The 
burning of wood is a chemical process in which oxygen of the air 
unites ^vith the chemical constituents of the wood. If the fire be 
banked or otherwise deprived of a liberal air supply, it smoulders. 
When air is liberally supplied, as through the stove drafts or 
forge bellows, combustion — and the resultant heat — are greatly 
increased, as a consequence of the increased supply of oxygen. 
The formation of humus in the soil, the fermentation of manures, 
and many other common phenomena of the fann, are in part pro- 
cesses of oxidation or burning on a small scale, and are dependent 
upon proper supplies of the oxygen of the air. 

Atmosphere controls rainfall. The atmosphere contains vary- 
ing amounts of water. Warm air has great capacity for holding 
water and may take up large amounts from the sea and inland 
lakes. Movements of this water-laden air control rainfall. In 
the case of the warm, moisture-laden winds moving eatward from 
the Pacific ocean, the water is released when the air is cooled on 
the snow clad summits of the Rocky Mountains. As a result, a 
large area east of the mountains, known as the Great American 
Desert, receives little or no rainfall and farmers are forced to 
irrigate or practice dry farming on arable land of this region. 

Atmosphere controls temperature. Dry air transmits heat 
readily from the sun to the earth or from the earth into space. 
For this reason the temperature falls rapidly after sunset in dry 
winter weather. Diy air also permits rapid evaporation of water 
from the earth's surface with consequent cooling. Moist air, on 
the other hand, prevents rapid evaporation from the earth's sur- 
face, absorbs heat transmitted from the sun and radiated from 
the earth, and thereby maintains higher temperatures. 

While the phenomena of temperature, moisture content, and 
movement of the air do not directly involve chemical processes, 
they have fundamental significance in the supplying of water and 
the maintaining of temperatures which regulate the chemical pro- 
cesses of plant growth. This significance has lieen a prominent 



The Atmosphere. 



25 



factor in the development of the present extensive "Weather 
Bureau service of the United States government. The records 
of this Bureau are of great service not only in predicting storms 
and frosts, hut in mapping restricted areas, such as the sugar beet 
belt, which will be favorable for certain crops dependent upon 
unifoi*m temperature and proper amounts of sunshine and rain- 
fall. 

Air is a mixture. A chemical compound is characterized by 
uniform composition. That is, the constituents of a single com- 
pound occur in the same proportions throughout its mass. This 
is not true for air, as the following table shows : 



Percentage Composition of the Atmosphere at Different Levels. 



Height in feet 



32S0 



32,800 



65, 600 



164,000 



328,000 



Nitrogen 

Oxygen 

Argon 

Carbon dioxide 



Per cent 

78.04 

20.99 

0.94 

0.03 



Per cent 

81.05 

18.35 

0.58 

0.02 



Per cent Per cent 



85.99 
13.79 
0.22 
0.004 



89.62 

10.31 

0.07 

0.00 



Per cent 

95.35 

4.65 

0.00 

0.00 



The air is a mixture of water vapor, gases, and solids in which 
the gases form far the greatest part. Since it is a mixture, the 
constituents are free to separate and, as the above table shows, the 
heavier constituents are absent in the higher layers. 

Composition of air. The average composition of dry air is as 
shown in the table on page 26. 

Water o£ the atmosphere. The water used by plants is taken 
up from the soil by way of the roots. Its passage through the 
plant and the escape of excess of water are regulated by the 
process of transpiration or evaporation from the surface of the 
leaves into the air. From the current of water thus maintained 
from the soil to the plant, growing crops assimilate all of their 
food except carbon dioxide. When the air is dry it absorbs water 
readily and promotes transpiration. Moist air, on the contrary, 



26 



Agricidhiral Chemistry. 



retards transpiration. By these influences over transpiration 
the air exercises control over plant growth. 

As has been stated, the presence of water in the air increases 
its capacity to absorb heat and w^hen the air is cooled it loses its 
power to retain moisture. Water then separates from it and 
collects upon colder objects. This is the cause of the appearance 
of drops of water on the outer surface of an ice-w^ater pitcher on 
a sultry day in sununer. Dew is formed in the same manner. 
After sunset on a warm summer's day the earth cools rapidly 
by radiation and reaches a temperature below that of the adja- 



The Average Composition of Drij Air. 



Per cent, bv weight 

Lbs. per 100 lbs. 

of air. 



Per cent, by volume 

Gals, per 100 gals. 

of air. 



Gases: Nitrogen 

Oxygen 

Argon 

Carbon dioxide 

Ammonia 

Nitric acid 

Ozone 

Solids: Dnst 

Bacteria 

Salts 




78.0 
21.0 
0.94 
0.03 
Trace 



cent air. At a temperature bearing a definite relation to the 
moisture content of the air and kno^vll as ''the dew point." 
moisture leaves the air and collects upon the surface of vegeta- 
tion and other cool objects. In rainless regions dew becomes an 
import^ant source of water for crops and frequent tilling must 
be practiced to prevent its escape by evaporation from the sur- 
face of the soil. 

Movements of the moisture laden air distribute rainfall over 
the land ; and some of the less prominent constituents of the air 
are washed to the soil by rain and become factors in the supply 
of plant food. 



The Atmosphere, ""27 

Gases of the air. Dry, pure air is essentially a mixture of 
gases. A gas differs from the more familiar forms of matter, 
as liquids and solids, in that its particles are much farther re- 
moved from one another, or as we say, it has less density. This 
relation is illustrated by the different forms which water may 
assume. When the solid substance knoAvn as ice is heated, its 
particles spread farther apart until it no longer has sufficient co- 
hesive power to retain its shape. It then melts and becomes the 
liquid known as water. Sufficient further heating, by separating 
the particles of water still farther apart, transforms it to the 
state of an invisible gas known as steam, which becomes a con- 
stituent of the gaseous atmosphere. When steam comes in con- 
tact with cold solid objects, or even with cold air, it contracts 
or condenses to visible water vapor. The gases of the air main- 
tain their rarified form under all ordinary conditions. They can 
be converted, however, like the air itself, to liquids, and even 
to solids, by subjecting them simultaneously to very low tem- 
peratures and high pressures. 

Nitrogen. This is the most considerable constituent of the 
air and amounts to more than three-quarters of the total weight, 
or about 30,000 tons over every acre of land. It is characterized 
by extreme inertness. When combined in chemical compounds 
it is frequently held "with difficulty. High power explosives de- 
pend for their value upon the ready and sudden release of a 
large volume of gaseous nitrogen from less bulky compounds as 
nitro-cellulose and nitro-glycerine. Since nitrogen is an essential 
constituent of compounds of the greatest importance in the living 
cells of plants and animals, its ready escape from such com- 
pounds has presented one of the greatest problems of agriculture. 

Relation of nitrogen to plant growth. The work of several 
able investigators has proved conclusively that higher plants can- 
not draw directly upon the great stores of nitrogen in the air for 
their supply of this element. 

In 1855 the French chemist Boussingault announced the re- 
sults of a series of carefully performed experiments to determine 



28 



AgncuUural Cliemistnj. 



this point. He grew plants for one and one-half to five months 
with no nitrogen supply beyond that in the seeds and the free 
nitrogen of the air. The seed was sown in a soil composed of 
ignited pumice stone and the ashes of manure, both having been 
freed from nitrogen compounds. The plants were grown in a 
glass jar sealed from the air but in connection with a supply of 
carbonic acid and were provided also with water free from nitro- 
gen. At the end of the experiments the nitrogen was determined 
in the plants and soil. 

The f ollow'ing table gives the results of five of the experiments 
and the average of the series : 



Kind of Plant. 



Nitrogen in 
Seeds. 



Nitrogen in 

Crop and 

Soil. 



Gain ( + ) or 

Loss ( — ) 
of Nitrogen. 



Bean 

Oat 

Lupin 

Lupin 

Cress 

Sum of 14 Experiments 



gms.* 
0.0349 
0.0(W1 
0.0200 
0399 
0.0013 
0.6135 



gms. 
0340 
0.0030 
0.0204 
0397 
0.0013 
0.5868 



gms. 
-0.0009 
-0 0001 
-f 0.0004 
-0.0002 

0.0000 
-O.0247 



*A gram is about one-twenty-eighth of an ounce. 

Since the gains or losses of nitrogen are within the limits of 
experimental error, Boussingault concluded, as a result of his 
work, that plants cannot use the free nitrogen of the air. 

This work w^as disputed by Ville, also of France, who grew 
plants in larger chambers and renewed the supply of air. He 
criticised Boussingault 's work for the limited amount of air 
used. Boussingault then proved by further experiments that 
plants raised under the conditions of his earlier trials only at- 
tained full development when supplied with assimilable com- 
pounds of nitrogen. An investigation of Ville 's experiments 
then showed that his results were vitiated by the presence of 
ammonia in his apparatus. 



The Atmosphere. 29 

The problem concerning the assimilation of free nitrogen was 
finally settled by an exhaustive study made in 1857 to 1858 by 
Lawes, Gilbert and Pugh at the Rothamsted Experiment Station 
in England. These investigators completed 27 experiments with 
cereals, legumes and buckwheat. The plants were grown under 
glass jars inverted in mercury to isolate them from the air. A 
supply of air, freed from nitrogen compounds and mixed with 
carbonic acid was forced through the apparatus and all nitrogen 
compounds were carefully excluded from the soil and water used 
in these experiments. The results fully confirmed the conclu- 
sions of Boussingault. 

In the course of other experiments it was observed that while 
supplies of nitrogen compounds in the soil stimulated the growth 
of cereals, they were without appreciable effect upon legumes. 
It remained for the German bacteriologist, Hellriegel, to dem- 
onstrate that leachings from soils cropped to legumes stimulated 
the growth of these crops on infertile soils, but failed to affect 
cereals. Then follov;ed the discovery of a remarkable affiliation 
of bacteria and leguminous plants by which the plants obtain 
supplies of nitrogen from the atmosphere. This discovery finds 
a practical application in the growth of leguminous crops in 
rotations for the purpose of maintaining the supply of nitrogen 
in the soil. In field experiments the soil supply of nitrogen has 
been maintained by growing clover in rotation with cereal crops. 
A small amount of nitrogen compounds also accumulates in the 
soil by the growth of bacteria which thrive independently of 
higher plants. 

Oxygen. This constituent of the air is prominent among the 
chemical elements because of its extreme activity. It combines 
with the waste products from plant or animal life in the process 
of combustion or decay and makes possible their destruction and 
removal. This process is frequently accompanied by perceptible 
heat, as in the rapid combustion of fuels, or the less active com- 
bustion of manures and silage. It is the source of heat in the 
animal body. The hardening of so-called ''drying oils" is alsO' 



30 



Agricultural Chemistry. 



a process of oxidation. These combine wdth the oxygen of the 
air, in some cases with sufficient rapidity to produce a rise in 
temperature causing spontaneous combustion. Destructive fires 
occasionally result from such oxidations. 

Oxygen usually forms about 28.2 per cent of the air by weight. 
"Where animal life is abundant or where much putrefaction is in 
progress, the percentage of it in the air will be reduced. On 





Clover obtaining its necessary nitrogen from the air through the aption 
of certain bacteria. No. 5 contains these bacteria, while No. 6 
does not (after Russell and Hastings). 

the other hand, being exhaled by plants, its proportion may in- 
crease slightly where vegetation is abimdant. 

Argon. This gas forms most of the remainder of the air. It 
closely resembles nitrogen in its properties. Argon is not known 
to be of any importance to agriculture. 

Carbon dioxide. Although usually forming a very small frac- 
tion of the air — 0.04 part, or less, by weight in 100 parts of air — 
this constituent is of great importance in agriculture. The aver- 
age green com crop of 12 tons per acre requires for its produc- 
tion 4 tons of carbon dioxide, which necessitates the respiring of 
10,000 tons of air, or about i/4 the amount available over that 



The Atmosphere. 31 

acre. This supply of carbon dioxide is assimilated from air taken 
in through the leaf pores or stomata. When united with water 
brought from the roots, it forms the basal compounds of the 
plant. The removal of this gas by plants is offset by its return 
from processes of combustion, fermentation, and animal respira- 
tion so that there is maintained a nearly constant proportion in 
the air. When produced by the decay of humus-forming mate- 
rial, it dissolves in the soil water and becomes a leading factor 
in liberating plant food from the mineral compounds of the soil. 

Ozone. This gas bears the relation to oxygen of O3 — Og — 
where O2 is the molecular symbol for oxygen. It is one-half more 
concentrated than oxygen and as a consequence is much more 
active. Ozone occurs in the air as a result of the action of 
electrical discharges upon oxygen. It acts as an antiseptic by at- 
tacking and destroying bacterial matter. Because of its great 
activity, it is rapidly exhausted and never amounts to more than 
a trace in the atmosphere. 

Nitric oxide. Traces of this gas accumulate in the wake of 
electrical storms. It is a compound of one part of nitrogen with 
one part of oxygen (14 parts of nitrogen with 16 parts of oxy- 
gen by weight), the formation of which is induced by electrical 
discharges. Nitric oxide readily unites with oxygen and water 
to form nitric acid and washes to the soil in the rain. Knop 
found ordinary rain water at Leipsig, Germany, to contain 56 
pounds of nitric acid in 10,000,000 pounds of water, while rain 
which fell during a thixnder shower contained 98 pounds in 10,- 
000,000. Nitric acid brought to the earth in this way is not free 
but combined with ammonia in the air. Reaching the soil as 
ammonium nitrate it is directly available to the plant. 

Ammonia. This gas accumulates in traces in the air as a re- 
sult of the decay of organic nitrogenous compounds. It is pro- 
duced in considerable amounts by the rapid fermentation of 
manures and in such cases may be detected by its pungent odor. 
It dissolves readily in water and washes to the soil in rains, gen- 
erally in combination with nitric acid. In this form its nitrogen 



32 Agricultural Chemistry. 

may be used directly by the plant or ultimately converted to 
nitrates. Ammonia from this source contributes but a small 
part of the nitrogen required by crops. 

The average amount of nitrogen brought to the soil per acre 
yearly by rain at the Rothamsted Experiment Station, over a 
period of 18 years was as follows: 

Nitrogen as nitrates and nitrites 11 lbs. 

Nitrogen as Ammonia 2 . (> lbs . 

Nitrogen in organic forms 1.0 lb. 

Total nitrogen 4 . 7 lbs . 

Obviously this supply of nitrogen falls far short of the 50 to 
100 pounds of nitrogen per acre required by different crops. 

Solids. The solids usually present in common air are sub- 
stances which have been taken up by the wind and remain sus- 
pended in finely divided condition. They include bacteria, yeast 
spores and other microscopic forms of plant life. These furnish 
the nitrogen already referred to as brought to the soil in "organic 
forms." The air contains dust particles from finely divided soil 
and this constituent is prominent in dr^^ regions. Spray from 
bodies of salt water, when taken into the air by \nnd, evaporates 
and leaves small quantities of salts suspended. These consist 
principally of sulphates and chlorides of sodium, potassium, cal- 
eiam and magnesium. Salts may be returned to the soil by rain 
in considerable amounts near the sea coast. Common salt is 
brought to the soil in this manner at the rate of 186 pounds per 
acre yearly at Georgetown, British Guiana ; at Rothamsted, Eng- 
land, which is farther inland, the amount is about 24 pounds per 
acre. Sulphur is an important element in the gro^^i;h of plants, 
and is brought to the soil by rain in the fonn of sulphates taken 
up from the sea. These supplies of plant food may become im- 
portant factors in the gro^rth of crops. It has been estimated 
that the chlorine in rain water at Rothamsted is sufficient for 
crops, with the possible exception of mangels, and that the sul- 
phur supplied in this way meets the demands of most cultivated 
crops. This high supply of sulphur may. however, be derived 



The Atmos'phere. 



33 



partly from extensive soft coal burning in a country like Eng- 
land. It is extremely doubtful if the sulphur supply from the 
atmosphere in the open country of the United States is as high 
as that found at Rothamsted. It is veiy probably much lower 
and not nearly sufficient for continuous crop requirements. 

Accidental constituents. In some localities the air contains 
uncommon constituents as a result of local conditions. This is 
true in active volcanic regions and in the vicinity of some indus- 




The effect of smelter fumes and waste on vegetation near Anaconda, 

Montana. 

trial plants. The most important of these constituents are gases. 
Methane or marsh gas, which is a product of fermentation where 
air is excluded and which accumulates over swamps and in mines, 
and carbon monoxide, a product from the incomplete combustion 
of coal, are exampl&s of this class. Hydrochloric acid gas. which 
escaped into the air in quantity from the old process of manu- 
facturing soda, is an example of an objectionable, accidental con- 
stituent of the air resulting from an industrial process. The 
deadly effect of this gas upon vegetation led to the passage of 



34 Agricultural Chemistry. 

laws restricting its escape. It is now condensed in the factory 
as a by-product of the industry. 

Sulphur dioxide is an accidental gaseous constituent of the 
air, the effects of which are of economic importance. It is ex- 
pelled from the stacks of smelters roasting ores which contain 
sulphur. It is also produced in small amounts wherever the 
combustion of coal takes place. It maj^ be partially converted to 
sulphur trioxide and brought to the soil by rain as a supply of 
sulphur for plants. The amount in the rain at Rothamsted was 
found to be about 17 pounds of sulphur trioxide yearly per acre. 

Experiments have demonstrated that sulphur dioxide injures 
plants through their leaves. Fumigation Anth one part of the 
gas to 100,000 parts of air has been fatal to scrub pines. In- 
vestigations have shown it to be the cause of serious injury to 
the vegetation in the vicinity of copper smelters in California, 
Montana and elsewhere. The foliage of injured trees in th&se 
vicinities was found to contain more sulphur than that of normal 
trees. Peach trees in an exposed position nine miles from a 
smelter at Redding, California, and red firs at a distance of fif- 
teen miles from the Washoe smelter, Anaconda, Montana, were 
badly injured. Analysis of the smoke from the latter smelter 
showed an output of 5,000,000 pounds of sulphur trioxide per 
day. Haywood, of the Bureau of Chemistrj'^, concludes that these 
fumes can be condensed and the products probably readily mar- 
keted. Legislation in the interests of forestry' should restrict 
the escape of this gas as it has in the case of hydrochloric acid. 



CHAPTER III 
THE SOIL. 

Soil is the layer of disintegrated rock, mixed with the remains 
of plants, which covers a large portion of the land. It also con- 
tains living organisms of various kinds and variable quantities 
of water and air. The depth of soils varies greatly, being usually 
from six to twelve inches, and sometimes as great as several feet. 
Beneath it is the subsoil which differs^ from the upper layer in 
containing less organic matter. The line of demarcation can 
often be distinctly seen in deep trenches by the difference in color, 
the subsoil being generally of lighter color, and gradually grad- 
ing into the dark color of the upper soil. 

Soils consist largely of disintegrated rock fragments and de- 
pend for their chemical nature mainly upon the character of the 
rocks beneath. The rocks have been classified by geologists ac- 
cording to their origin into three classes : 

(1) Igneous rocks are those which resulted from the cooling 
of intensely heated matter. The granites represent this type. 

(2) Sedimentary rocks are those resulting from the settling 
out of particles suspended in water. Limestones are examples 
of this type. 

(3) Metamorplvic rocks are those which have been changed in 
character since their deposition. The conversion of limestone 
into marble by pressure and heat is an illustration of this type. 

These rocks must have contained all of the mineral or ash ele- 
ments of plant food as no other source for them is conceivable. 

Rocks are rarely homogeneous, that is, alike in all parts — but 
are generally made up of several components mingled together, 
often lying side by side as separate crystals. These components, 
which have a more or less definite composition, are called min- 
erals. Distinctly separate minerals are more frequently to be 
seen in the igneous rocks. A piece of granite will readily show 
that it is made up of several distinct minerals. 



36 Agricultural Chemistry. 

Minerals. The follos\ing minerals are abundant and of the 
greatest importance to agriculture: 

Quartz is chemically a compound of silicon and oxygen. It 
is estimated that it forms 35 per cent of the solid crust of the 
eartli. It is one of the hardest and most durable of substances 
and is practically insoluble in water and but little affected by 
the weather. Sea sand and the sands along the shores of our 
fresh water lakes are often almost wholly made up of fine grains 
of quartz, worn smootli by continuous agitation to which they 
have been subjected. Fragments of quartz, consisting of crystals 
rounded and worn by mechanical rubbing against each other, 
form the largest constituent of many soils. Such sand is lack- 
ing in plant food. 

Feldspars are probably the most abundant of all minerals and 
constitute, it is estimated, 48 per cent of the earth 's crust. Chem- 
ically, the feldspars contain silicon, oxygen and aluminum in 
combination M'ith either sodium, potassium, or calcium, and are 
called by the chemist, silicates. 

The chief varieties of feldspars are 

Orthoclase potassium aluminum silicon oxygen 

Aibite sodium aluminum silicon oxygen 

Labradorite sodium aluminum silicon oxygen 

calcium 

Orthoclase or potash feldspar is the most important. It is a hard 
mineral, often colored pink or green, though sometimes white. 
Although hard, it is easily attacked by water and carbon dioxide, 
the potassium being largely removed in solution while the final 
residue is kaolin or China clay. Orthoclase furnishes a consider- 
able quantity of the potash found in our soils. 

Mica is another abundant mineral and characterized by its 
tendency to split into thin elastic plates. It is essentially a com- 
pound of aluminum, potassium, silicon and oxygen, though it 
usually contains iron and often calcium or magnesium. Mica 
also suffers decomposition under the influence of the weather, 
but not so readily as the feldspars. It furnishes plant food in 



The Soil. 37 

the iron, potassium and calcium it contains. Its amount in the 
earth's crust has been estimated at 8 per cent. 

Silicates of magnesia are also very abundant. Talc and 
steatite are representatives of this class and are compounds of 
magnesium, silicon and oxygen, designated by the chemist "sil- 
icates of magnesia. ' ' They also contain water. When the mag- 
nesium is partly replaced by other elements, as calcium, iron or 
manganese, we have the distinct minerals knoAvn as hornblende 
and augite. Ail the minerals of this class are easily acted upon 
by water and air and often yield brightly colored clays due to 
the presence of iron. 

Calcium carbonate occurs in a great many crystalline forms, 
the principal variety being called calcite, and in the massive form 
is kno^\Ti as chalk, limestone and marble. These are all essen- 
tially made of calcium, carbon and oxygen, but in certain local- 
ities the calcium is more or less replaced by magnesium which 
then gives us the mineral known as dolomite. This is true of 
many of the ''limestones" found in "Wisconsin. Most calcium 
carbonates contain notable quantities of phasphoric acid. Cal- 
cium and magnesium carbonates, though only slightly soluble in 
pure water, are readily soluble in water containing, as in the case 
of nearly all forms of natural water, carbon dioxide. Rocks con- 
taining these substances therefore are quickly eroded by exposure 
to the atmosphere. Calcium carbonate is of great importance in 
soils, both on account of its providing plant food and because 
of its relationship to many of the processes which go on in soils. 

Clay in its pure form is a hydrated silicate of aluminum and 
is therefore devoid of plant food. By the term hydrated we 
mean that the compound of silicon, aluminum and oxygen (sili- 
cate of aluminum) is joined to a certain amount of water. Or- 
dinary clay, however, contains iron and potassium, the latter re- 
maining from the feldspar, from which most clays have been 
formed. It therefore supplies potassium to plants. Its physical 
properties are very important and greatly influence soils in 
which it is abundant. 



38 Agricultural CliemiMry. 

Apatite or ciystalized phosphate of lime, is present in small 
quantities in many of the older rocks, and is probably the original 
source of the phosphoric acid of soils. Apatite also occurs mas- 
sive in some of the older rock formations and is mined as a raw 
material for the manufacture of phosphate manure in Norway. 
Canada and particularly in some of our southern states, as Flor- 
ida, the Carolinas, Georgia and Tennessee. 

A brief descrii)tion of some of the more important rocks will 
now be given. The igneous rocks are the oldest and it was from 
the debris of igneous rocks that sand stones, shales and, indirect- 
ly, limestones were formed. 

Sand stones and grits, consist of the larger fragments of the 
waste resulting from the breaking up of igneous rocks, as for 
example granite, which in consequence of their size and weight 
have been deposited at or near the mouths of rivers. Their main 
ingredient is silica, the grains of sand consisting largely of quartz 
crystals, but in many cases fragments of feldspars, mica and 
other minerals are present. These grains are cemented together 
either by calcium carbonate, as in calcareous sand-stones, by clay, 
as in argillaceous sand-stones, by iron oxide, as in ferruginous 
sand-stones, or by silica, as in siliceous sand-stones. Soils pro- 
duced by the decay of sand-stones are light and friable and poor 
in plant food unless there is present potassium-containing min- 
erals as feldspar and mica. 

Shales consist principally of the plastic hydrated aluminum 
silicate, kaolin, but maj* contain any other extremely finely di- 
vided matter obtained by the erosion of the original rock. Par- 
ticles of undecomposed or partially decomposed feldspars are 
often present and these are of importance because of the potash 
they contain. Soils formed from shales are "heavy" and clayey, 
generally sufficiently rich in potassium, but poor in phosphorus 
and calcium carbonate (lime). 

Limestones, in which term chalk and magnesian limestone may 
also be included, have been formed largely by the abstractioTi 
from water by living organisms, as coral polyps, shell fish, etc.. 



Tlie Soil 39 

of calcium and magnesium carbonates. Oyster shells are prin- 
cipally a calcium carbonate. Limestones often contain small 
quantities of clay, iron oxide, silica and nearly always calcium 
phosphate in comparatively large quantities. The soil left on 
limestone or chalk consists mainly of these foreign substances, 
most of the calcium carbonate itself having been dissolved out 
by the combined action of water and carbon dioxide. It some- 
times happens therefore that the soil originating on limestone 
would be benefited by an application of limestone. 

Limestone only exerts its characteristic and important func- 
tions in a soil when in a very finely divided state. In the form 
of gravel or sand it is little better than ordinary siliceous sand. 
In the finely divided state it has two very valuable functions; 
first, as a source of plant food by virtue of the calcium which it 
contains, and second, which is more important, as a basic material 
necessary for the correction of an acid reaction in the soil and 
for the processes of nitrification. 

Sedentary and transported soils. These terms are convenient 
in distinguishing between soils which have been made up of the 
debris resulting from the weathering of the particular rock on 
wliich they rest (sedentary soils) and those which owe their 
origin, not to the rock below them, but to materials brought from 
a distance and deposited there (transported soils). The rich 
alluvial soil in the lower reaches of river valleys consists largely 
of material which has been brought down by the river from the 
higher parts of the valley and since the materials in many cases 
have been brought from various rock formations, the resulting 
soil generally possesses a greater fertility than would be shown 
by soil formed exclusively by the weathering of any one kind of 
rock. 

Glaciers are also the means of transporting large quantities oi' 
materials out of which soils may be formed. Large tracts of 
country are covered with a thick deposit of clay and rock frag- 
ments, which have been brought from a great distance by glaciers. 
Such deposits are known as glacial drift, and often quite obscure 



-10 



Agricultural Chemistry. 



the actual rock beneath. In this case the transportation of the 
soil took place many ages ago. A large part of northern United 
States is covered by drift, which was pushed down from the north 
by the glaciers that once covered that section and was left behind 
as the ice melted away. Such soils are distinguished from all 




The weathering of rock into sub-soil and soil (after Hall) 



others by the presence of rounded boulders of various sizes. 
They are usually fertile, although very variable in composition. 

Wind also sometimes acts as a means of transporting sand, 
volcanic ash, etc., from a distance and deposits them in a new 
position, there to form a soil. 

Formation of soil. In the formation of a soil the first step 
is the mechanical breaking down of the rock into small fragments. 



The Soil. 41 

The chief agencies by which this is accomplished are, first by 
Water, which acts in several ways. 

Mechanically, by liquid water — The flow of water over the 
surface of a rock abrades it slightly. The action is greatly in- 
creased by the rubbing action of pebbles and gravel, urged on 
by the current over the rock. In this way streams in the rapid 
portions of a course carry away large quantities of sand, gravel, 
etc., and deposit them in the lower and quieter portions of their 
course as alluvial deposits. By glaciers — Glaciers are slowly 
moving masses of ice. In their descent, aided by fragments of 
rock imbedded in them, they grind away the rock over which 
they pass and the stream which flows from the base of a glacier 
is always heavily charged with the finest mud, while the lowest 
point reached by a glacier is marked by huge piles of rock frag- 
ments of all sizes, carried down on the surface of the moving ice. 
By alternate frost and thaw — Ice occupies a greater volume than 
the water from which it is formed. The increase in volume in 
the act of freezing amounts to about 10 per cent and unless this 
increase is allowed to occur water cannot freeze, however much 
it be cooled. This is a powerful agency in the pulverization of 
rocks. All rocks are more or less porous and absorb water. 
During the warm part of a wet winter's day the crevices of a 
rock become filled with water. If the temperature falls the 
water begins to freeze, at first on the surface so that every crevice 
becomes plugged with ice. As the liquid within continues to lose 
heat it tends to solidify. This it can only do if it be allowed to 
expand and in order to do this it must widen or lengthen the 
crevice. When the next thaw comes, the enlarged crevice again 
fills with water. The next freeze repeats the action and so the 
process goes on until the hardest rock is broken into fragments. 

Chemically. Many minerals when exposed to the action of 
water are acted upon in such a way as to h.-ad to their disintegra- 
tion. A portion is often carried away in solution while the re- 
mainder crumbles and is then easily moved by rain or running 
water. In many rocks the cementing material, which holds the 



42 Agricultural Chemistry. 



I 



grains together, is dissolved away and the residual fragments 
then readily crumble. 

A soil produced by mere mechanical pulverization of the rocks 
would not furnish proper food for the higher plants. This can 
readily be imagined if one thinks how unsuitable crushed granite 
would be for plant production. The essential elements locked 
up in these insoluble soil-forming materials must be changed into 
materials that the plant can assimilate and water is an important 
factor in bringing about such chemical changes. The minerals 
forming our igneous rocks are, however, very slightly soluble in 
pure water; but the water that enters the ground has dissolved 
in it small amounts of carbon dioxide, derived from the air, and 
water containing this gas will dissolve these minerals in appre- 
ciable quantities. 

Another important agent in soil formation is the air, which 
acts in several ways. 

Mechanically. Wind actually' detaches large projecting pieces 
of rock in mountainous districts and sends them crashing doAvn 
onto the rocks below. In addition, by hurling sand and small 
Peebles against the surface of rocks it brings about the erosion of 
the latter. In most cases the effects of this form of erosion are 
ma.sked and hidden by those of other denuding agencies. 

Chemically. In many rocks are minerals capable of taking up 
oxygen. On exposure to air, oxidation occurs and the mineral 
swells up and often crumbles to powder, thus loosening the other 
minerals in the rocks. This oxidation is in many cases accom- 
panied by a change in color, from green or gray to yellow or 
red. The carbon dioxide of the air also acts corrosively on car- 
bonates in the presence of water. 

Animals are also imjiortant agencies in soil formation. Bur- 
rowing animals, as for example, rabbits, moles, etc., admit air 
into soil or sand and thus favor the changes which air produces. 
The ]):\v\ i)l;iy('(l l)v Ww humbler creatures, earth worms, is prob- 
ably much more imi)ortant. They bring portions of the subsoil 
to the surface, tliey draw dead leaves and other vegetable refuse 



The Soil 43 

into their burrows, and they pass large quantities of the soil 
through their bodies and deposit it on the surface at a rate which 
has been estimated on the average to be about ten tons per acre 
per year. 

Ants in some hot countries, as for example Africa, perform 
much the same work as earth worms, though perhaps on even a 
larger scale. Ingle says that in many parts of South Africa, the 
veld is thickly studded wdth the hills of the white ant, usually 
about two feet high and about two to three feet in diameter,^ 
though much larger ones are often found. The ant hills are full 
of cavities and chambers inhabited by the insects and much 
vegetable matter is stored in them. The material of the ant hills 
consists of the smaller parts of the surrounding soil, the par- 
ticles being cemented together and the whole made practicall;v 
water tight. "When the veld is plowed and sown, it is always 
noticed that where ant hills had formerly been the crop is heavier 
than elsewhere. 

Plants act as soil formers in several ways: MecJianically — -the 
roots penetrate the rocks or soils, rendering them porous and thus 
admitting air and water. They also exert a tremendous lateral 
force, breaking apart rocks and stones when once they have ob- 
tained a foothold in a crevice. The roots penetrate the soil some- 
times to great depths, and as they decay, afer the death of the 
plant, they leave in the soil little channels, which serve to carry 
down water laden with carbon dioxide, as well as the oxygen 
of the air, which as previously pointed out are important factoids 
in soil making and the production of available plant food. 
ClicmicaUy — plants act during life through the corrosive action 
of the carbon dioxide excreted by the roots and root hairs and 
after death by producing carbon dioxide and various vegetable 
acids, which have solvent properties upon certain constituents 
of soils. 

The formation of a mass of pulverized rock, however, is not 
all that is necessary for producing a fertile soil. A fertile soil 
must contain nitrogen. It has been shown that to grow crops the 



44 



Agricultural Chemistry. 



soil must contain available nitrogen, and this must have been de- 
rived originally from the air. Small quantities of combined 
nitrogen, as stated in a previous chapter, are carried into the 
ground by the rain water and though small in amount, are prob- 
ably sufficient to enable plant growth to begin. Bacteriologists 
believe that certain species of bacteria, which can live on mineral 
food alone and derive all their nitrogen supply from the air were 
the first agencies and are still important factors in accumulating 
the nitrogen supply of the soil. Certain simple forms of plant 




Diagram illustrating the formation of a soil on a limestone hill (after 

Vivian). 



life, as lichens and mosses, it is believed, can also derive their nit- 
rogen from the atmosphere. "When, after death, a plant becomes a 
|)art of the soil, all the plant food it contained is returned. Food, 
once used by plants, is readily made available to succeeding crops 
through processes of decay and nitrification. The soil is thus 
made richer and more fertile. In this way growth gradually 
becomes more abundant. The plants upon decay give rise to 
''humus," the chief nitrogen containing body of the soil and 
from which the higher plants, through annnonification and nit- 
rification, derive their necessary supply of nitrogen. 

Legumes enrich soil with nitrogen. This particular class of 
plants to which the clovers, alfalfas, vetches, lupines, peas, and 



The Soil. 45 

beans belong, is able, through the agency of nodule forming bac- 
teria growing on the roots, to derive nitrogen from the inex- 
haustible stores of the atmosphere. This peculiar property of 
leguminous plants is quite distinct from the requirements of all 
other farm crops, which acquire their nitrogen from the nitrogen 
compounds already in the soil. This fact is of the greatest im- 
portance to agriculture, for it is '^ Nature's principal method'' 
of increasing the nitrogenous food in the soil. The nitrogenous 
compounds stored in such plants eventually become a part of the 
soil through their decay, thus furnishing food for other plants 
and increasing the fertility of the soil. 

The constituents of soil. A popular and convenient classifi- 
cation of soil constituents is the following : 

(1) Sand — mainly silica, but containing small fragments of 
feldspar, mica, and other minerals. 

(2) Clay — mainly kaolin, but containing small fragments of 
silica, feldspar, etc. 

(3) Limestone — finely divided calcium carbonate. 

(4) HvAHUs — the somewhat indefinite niti'ogenous and carbon- 
aceous material, bro\A'n or black in color and resulting from the 
decay of plants. A brief description of these materials will now 
be given. 

Sand is of low specific heat and has the lowest water retaining 
power of all soil constituents. It is practically valueless as a 
plant food, except for the small amounts of potassium, calcium 
and iron contained in the mineral fragments mixed with the time 
sand. Its physical properties often have valuable effects upon 
the character of a soil, particularly with regard to friability, and 
its relation towards water and heat. 

Clay in its pure form is free from plant food, but is usually 
well supplied with potash, because of the feldspar present. Com- 
mon clay contains quartz and calcium carbonate (as in marls) 
in addition to feldspar. The true clay (kaolin) acts as a cement 
to the other mineral grains. ' 

It is thought that even in the purest clay there is a small quan- 



46 Agricultural Chemistry. 



i 



tity of aluminum silicate containing more water than the rest, 
to which the plasticity and tenacity of clay is due. If this con- 
stituent is fully swollen with water the clay is impervious and 
sticky, while if it is shrunken or coagulated the clay becomes 
more friable and l&ss plastic. Calcium compounds are partic- 
ularly effective in inducing such coagulation and it is to this 
(^ause that the improvement in texture of heavy clays by lime 
applications is due. 

Lime stone. Calcium carbonate is present in the soil in a fine- 
ly divided state distributed among the other constituents, but in 
addition there may be larger fragments which are classed with 
the "sand." The finely divided material is the one of import- 
ance. It furnishes plant food, for the plant must have calcium, 
but it also plays other important functions. It modifies the 
plasticity of clay in the manner described above and in addition 
neutralizes any acids accumulating in the soil. Acids are pro- 
duced by the decay and fermentation of vegetable matter, and 
if allowed to accumulate, will render the soil unfit for max- 
imum crop production. Such soils are spoken of as "sour" and 
can best be restored to fertility by the application of quick lime 
or ground limestone. Limestone performs another important 
function by acting as a basic material necessary for the process 
ImoAvn as nitrification, to be explained later. 

Limestone also serves an important fimction in those soils 
Avhich have received applications of the commercial fertilizer, 
ammonium sulphate. It prevents the accumulation of sulphuric 
acid, which otherwise would make the soil sour, by its power to 
neutralize this acid. The neutral salt formed — calcium sulphate 
— partly runs off in the drainage water. 

Humus is the brown or black organic matter of surface soil. 
It is the product formed by partial decay of organic matter and 
is the material that gives the rich black appearance to some soils. 
It is formed from the residue of plants previously grown on the 
soil or from added organic matter in farm manures or commercial 
fertilizers. It is a mixture of many ill-defined bodies. Besides 



The Soil. 47 

the nitrogen contained in it, there is always found in its ash, 
such plant food elements as phosphorus, potassium, iron and 
sodium, together with silicon and aluminum. These ash consti- 
tuents are thought to be of considerable importance because they 
are apparently easily available to plants. 

The humus of soils is of the greatest agricultural importance. 
It not only modifies its physical properties, but is the principal 
storehouse for nitrogen. A soil rich in humus is rich in nitro- 
gen ; a soil poor in humus is poor in nitrogen. The plant does 
not use it directly, but its nitrogen must first be converted by 
bacteria into water soluble forms, such as nitrates, before it is 
available. By the decay of humus the proportion of carbon diox- 
ide in the soil water is increased and thus the solvent powers of 
the latter for plant food in the mineral portion of the soil are 
enhanced. 

Virgin soils are comparatively rich in humus, but continuous 
cropping with no return to the soil of humus forming materials 
may result in its being decreased from one-third to one-half in 
a period of not more than fifteen years. The amount of humus 
in soils is variable, dependent upon such factors as climate and 
the previous soil treatment. In humid regions ordinary arable 
soils vary in humus content from 2 to 5 per cent. Swampy, 
peaty, and muck soils contain larger amounts. In a bog soil the 
per cent of humus may be as high as 30 per cent. In arid re- 
gions the amount of humus in the soil is normally less than found 
in our humid regions, the amount rarely exceeding 1 per cent. 

These materials described above have great influence upon 
both the physical and chemical properties of soils. The import- 
ant physical properties of the constituents themselves are shown 
in the table on page 48. 

The explanation of the terms (used in the table are as fol- 
lows: Specific gravity is the weight of any volume of the 
solid material compared with that of an equal volume of water. 
Specific heat (equal weight) is the ratio of the amount of heat 
necessary to raise the temperature of a certain quantity of a 



48 



AgHcultural Chemistry. 



substance compared with that required to raise an equal weight 
of water through the same range of temperature. Specific heat 
(equal volume) is the relative amounts of heat required to raise 
equal volumes of the material and of water through a given range 
of temperature. 

Physical Properties of Soil Constituents. 



n 



Specific 
Gravity 



Specific Heat 
Equal 
Weight 



Specific Heat 

Equal 

Volume 



Water held 
by 100 parts 

by weight 
of substance 



Water.... 

Sand 

Clay 

Limestone 
Huraus. . . 



1.00 
2.62 
2.50 
2.60 
1.30 



.000 
.189 
.233 
.206 
.477 



1.000 
.499 
.568 
.561 
.587 



25 

70 

85 

181 



From the above table we see that the same quantity of heat 
will raise 1 pound of water and 5 pounds of limestone or sand 
to about the same temperature, or if we consider only the solid 
constituents of soil, the same amount of heat will raise 3 pounds; 
of humus and 8 pounds of sand to the same temperature. 

Relation to heat. The sources of heat to a soil are the sun and 
(.'heinical changes within the soil. The chemical oxidation of 
organic matter in the soil will slightly raise the temperature, but 
by radiation are largely influenced by weather conditions. Ex- 
tremes of heat and cold occur with a clear sky and dry air. In 
a cloudy, moist climate, the variations in temperature are com- 
paratively small. At mid-day the power of the sun's rays is at 
depth of 1 foot, the average temperature of the soil, after a lapse 
of 20 days was 2.3° higher than that of unmanured soil. Dur- 
ing the next 5 days the excess of terni)erature wa.s only 0.8°. 
Chemical action is at its height during the summer months. 

The amount of heat received from the sun and the amount lost 
the effect is generally slight. In an experiinciit at Tokio, Japan, 



The Soil. 49 

where 40 tons of manure were incorporated with the soil to a 
its maximum. They then pass through a minimum thickness of 
the atmosphere. At sunrise they are weakened by diffusion over 
a wide area and in addition are diminished in intensity by ex- 
cessive atmospheric absorption. The difference in the angle of 
incidence of the sun's raj^s is the principal cause of the difference 
between a tropical climate and that of Wisconsin. The slopes on 
our own fields often offer examples of such effects. It is on a 
slope facing south that the soil wall reach its highest temperature 
during sunshine. 

A dark colored soil becomes warmer in the sun's rays than a 
light colored one, a larger proportion of the sun's energy being 
absorbed and converted into heat. No difference will be observed 
on cloudy days. At night all soils will cool to the same point. 

When a soil is freely exposed to the sky the temperature at the 
surface will reach a higher maximum and fall to a lower min- 
imum than the air above it. Schuebler found that the freely ex- 
posed soil in his garden at Tuebingen, Germany, averaged at 
one-twelfth inch below the surface, shortly after noon and in per- 
fectly clear weather, about 120° Fahr. for every month from 
April to September inclusive, and in July reached 146° ; this 
latter temperature was 65° above that of the air taken at the 
same time. 

With dry soils, including only hygroscopic water, about 3 cubic 
feet w^ould be heated by the sun to the same degree as one cubic 
foot of water. In this condition there is little difference between 
different soils; a dry peat will consume the least heat and a dry 
clay the most. When, however, soils become wet great differ- 
ences appear. In a freshly drained condition, a coarse gravel or 
sand will warm to a greater depth, while soils retaining more 
water will warm to a less depth. The specific heat of wet peat 
does not differ greatly from that of its own bulk of water. 

The depth to which a soil will be heated depends, however, 
partly on the conductive power of its constituents. Sand has the 
greatest power of conducting heat of any soil constituent. Air, 



50 Agricultural Chemistry. 

present in the soil, is the worst conductor. A dry soil is thus 
a very poor conductor of heat. Consolidation improves the con- 
ductivity. Wetting the soil doubles the conductivity of sand, 
limestone, or clay by displacing the air. We see then, that a 
dry, loose soil will get very hot at the surface when exposed to 
the Sim, but the heat will penetrate to a slight depth. This ex- 
plains why gravelly soils are best suited for early spring crops. 

Presence or absence of much water is the important factor 
which chiefly determines the cold or warm character of a soil. 
A still more potent reason for the coldness of wet soils, is, how- 
ever, the loss of heat during evaporation. When a pint of water 
is removed by evaporation from 97 pints, the 96 remaining pints 
will have fallen 10° Fahr. in temperature unless this amount of 
heat has been supplied from some external source. Undrained 
meadows and heavy clays consequently are cold soils because 
much of the sun's heat is, in these cases, consumed in evaporating 
water. Parks found that an undrained peat bog 30 feet deep, 
had a temperature of 46° when measured below a distance of 
1 foot from the surface. In the middle of June he found the 
temperature 47° at 7 inches below the surface, while the drained 
portion had a temperature of 66° at this depth, and a tempera- 
ture of 50° at 2 feet below the surface. Draining is the only 
cure for a cold, wet soil. 

The temperature of the subsoil is practically constant through- 
out the year at a certain distance from the surface. Observations 
at Greenwich Observatory, England, in a well drained gravel, 
showed that the variations of day and night are slightly felt at 
3 feet from the surface. At 251/2 feet the maximum temperature 
usually occurs in the latter part of November and the minimum 
in the first week in June. The difference between the two is 
about 3°. These observations make it clear that the soil and 
subsoil are generally warmer than the air in autumn and cooler 
than the air in spring. 

Tenacity of soil. The tenacity of a heavy soil is due to the 
fine silt and clay. The coarser elements of a soil, such as a fine 



The Soil. 51 

sand, exhibit little cohesion. Clay owes its cementing power it 
is believed, to the presence of a small quantity of a hydrated col- 
loid (jelly-like) body, which according to Schloesing rarely ex- 
ceeds 1.5 per cent of the clay. The remainder of the clay is com- 
posed of extremely fine, solid particles. In the purest natural 
clays, all the constituents have the same general chemical com- 
position, that is, they are hydrated silicates of aluminum ; but in 
soils the non-colloid constituents of the clay may be of a very 
various nature. In brick clay this material is quartz sand; in 
marl it is limestone. 

The condition of clay soils depends much on whether the clay 
is coagulated or not. When the clay is uncoagulated, the soil is 
sticky, impervious to water, and cannot be reduced to a fine tilth. 
When a clay is coagulated the soil has a granular structure, is 
pervious to water, and can be reduced to powder. It is coagu- 
lated by lime and by many salts, and especially by salts of cal- 
cium. Colloid clay will remain permanently suspended in dis- 
tilled water. It is precipitated by the addition of a small quan- 
tity of a calcium salt. An application of lime to clay soils is 
well known to be extremely effective in diminishing their ten- 
acity, rendering them pervious to water, and more easy of tillage. 

In cultivated sandy soils humates are often of great value as 
cementing materials; these, like true clay, are colloid bodies. 
Schloesing found that 1 per cent of a humate, as calcium humate, 
was as effective as a cement for sand as 11 per cent of clay. 
Humates, however, will lose their cementing power on drying, 
while clay will not. The improvement of the texture of sandy 
soils by the continued use of farm yard manure, or by the plow- 
ing under of green crops, is a fact familiar to the farmer. While 
applications of humus forming materials, as the above, increase 
the coherence of sand, they have an opposite effect on clay, and 
are the most effectual means at the disposal of the farmer for 
lightening a heavy soil. Lime will also tend to increase the co- 
herence of sand. 



52 Agricultural Chemistry. 



n 



Relation to water. We have learned that a good soil consists 
of solid particles of fairly imiform size. The spaces between 
these particles constitute about 40 per cent of the volume. If 
the particles are a mixture of large and small, as for example 
gravel and sand, the volume of these spaces is much reduced. On 
the other hand if the particles are themselves porous, as in the 
case of chalk, loam, and especially humus, then the volume of 
the spaces is increased. It is this volume of the inter-spaces 
which determines the amount of water which a soil will contain 
when perfectly satiu-ated, or the amount of air which it will con- 
tain when dry. 

Humus increases the capacity for a soil to absorb and retain 
water and consequently a crop grown on a soil containing a fair 
amount of humus is less likely to suffer from drought. The fol- 
lowing table illustrates this point. It gives the amount of water 
held by 1 cubic foot of different varieties of soil ; 

Lbs, of water in 
Kind of Soil 1 cubic foot 

Sand 27.3 

Sandy Clay 38 . 8 

Loam \\A 

Humus hO.\ 

Farm crops will not grow in a soil permanently saturated with 
water and from which air, consequently, is excluded; the best 
gro^^i:h is obtained from soils one-half or two-thirds saturated. 
The surface of a soil is seldom saturated, except immediately 
after a heavy rain; it is the quantity of water which a soil ^vill 
retain when fully drained which determines its capacity for sup- 
plying a crop with water. The amount of water pennanently 
retained by a soil does not depend upon the volume of the inter- 
spaces, but upon the extent of internal surface, the water being 
held by adhesion as a film on the surface of the particles. The 
smaller, therefore, the particles of a soil, or the more porous, the 
grcMtcr is the nnionnt of water retained. Two samples of pow- 



The Soil. 53 

dered quartz, one coarse, the other very fine, will hold Avhen 
saturated, more than 40 per cent of their volume as water. But 
when drained, the coarse sand will retain about 7 per cent while 
the fine quartz holds 44.6 per cent of water. The latter will 
loose, in fact, no water by drainage. 

Gravels and coarse sand retain the least water M^hen drained. 
As the particles become smaller, the retention of water increases. 
Colloids, jelly-like bodies, as clay and humus, increase the power 
of retaining water, as such bodies swell up when wetted and hold 
the water in jelly-like substances. The addition of humus to 
soils is one of the best Avays of increasing their water retaining 
capacity. 

Water from below may supply a surface soil if a saturated sub- 
soil exists at a moderate distance. Such water is said to be 
raised by capillary action, which simply means that the surfaces 
of the soil particles exert an attraction for water. The finer the 
particles and the closer they are packed, the greater the height to 
which water will be carried by capillary action. When the dis- 
tance it has to travel increases, the quantity reaching the surface 
diminishes. When the fineness of the particles exceeds a certain 
point the quantity of water raised also diminishes. It is not 
always the soil with the finest particles that brings most water 
to the surface. There is a certain degree of fineness of soil par- 
ticles that acts most effectively. Capillary action is seldom able 
to maintain a sufficient water supply at the surface. In Wiscon- 
sin every few years crops suffer from drought, although a per- 
manent water supply exists several feet below the surface. Cap- 
illary action is most effective in the case of silty soils ; such soils 
were deposited from running water and consist of very unifoi^m 
particles, but without any true clay. Some western soils, which 
are capable of growing wheat with a winter rainfall of 10 to 12 
inches and a continuous summer drought of three mouths' dura- 
tion, are deep, fine grained, and uniform, with practically no 
particles of the fineness of clay to check the upward lift of 
capillarity. 



54 Agncullural Chemistry. 



1 



The evaporation from a saturated soil is greater than from a 
water surface and as the soil drys the rate of evaporation rapidly 
diminishes. The average annual evaporation from a bare loam 
at INIadison. AVisconsin, is about fifteen inches. While soils of 
various character evaporate equal amounts while saturated, 
they exhibit great differences as drying proceeds. A soil of 
coarse particles and loose texture dries quickest and to the 
greatest depth. Consequently it appears to be good practice 
to avoid deep tillage in earh' summer, if land is intended to carry 
a crop. 

Evaporation from the soil is diminished by protection from 
sun and wind. Economy of water is best effected by mulching 
with straw. Keeping the surface stirred to a depth of an inch 
or two, thus providing a mulching of loose dry soil, is an excel- 
lent practice and forms a fundamental part of successful culti- 
vation in dry climates. 

The greatest evaporation of water takes place from the soif 
when it grows a crop. The water in a soil growing barley and 
in an adjacent bare fallow was determined at Rothamsted, Eng- 
land, at the end of June during the drought of 1870. It was 
found that down to 54 inches below the surface the barley soil 
contained 9 inches less water than the fallow soil. The injurious 
effect of weeds in the summer time is largely due to their robbing 
the soil of water. 

"With dry soils the farmer should aim to increase the amount 
of humus. Crops should be sown early and the land kept solid ; 
very shallow summer cultivation should be resorted to. Such 
land may po.ssess distinct advantages. It furnishes the earliest 
crops to market gardeners, the soil being easily warmed. A little 
rain will wet it to a considerable depth and the whole of the 
water it contains is available to plants. 

A soil, when drained, is seldom too wet because of its power to 
retain water. The trouble is more often due to want of drain- 
age ; the remedy for such a soil is deep tillage and draining. Ap- 
plications of lime or an increase in the humus content may be 



The Soil 55 

an effective means of rendering the surfai^e soil more pervious 
to water. 

The wettest soil does not always supply the largest amount of 
water to a crop. A peaty soil holds most water, but it is held 
so firmly by the colloid matter as to be unavailable to plants. 
A stiff clay fails in a drought as the water in this class of soils 
is also firmly held and moves with difficulty. Soils composed of 
silt or extremely fine sand are those which yield water most 
effectually to a growing crop. 

Chemical changes occurring in soils. The chemical changes 
going on in soil are numerous and complex. The mineral matter 
is subjected to the same influences as led to its breaking down in 
the formation of soil from the original rock. These changes are, 
however, hastened because of the great quantity of carbon di- 
oxide produced by the decay of organic matter. Fragments of 
feldspar are decomposed with formation of silicic acid, potassium 
carbonate and kaolin or clay. The clay remains behind, but the 
silicic acid and potassium carbonate may in part be dissolved and 
either carried away in the drainage, or may be absorbed by the 
roots of plants or by some of the absorptive constituents of soils. 
Calcium carbonate or limestone is dissolved by water containing 
carbon dioxide, which is true of all soil waters, and is in part 
carried away in the drain or absorbed by certain soil constituents. 

Calcium phosphate, as it exists in minerals, is nearly insoluble 
in water, but through the action of the soil water containing 
carbon dioxide in solution, it is changed to more soluble forms 
and therefore becomes available to plants. In contact with cer- 
tain forms of iron and aluminum in the soil the soluble calcium 
phosphates may be changed to iron and aluminum phosphates 
and held back in the soil in finely divided condition, and though 
then quite insoluble in water, may still be dissolved by the acid 
juices of the plant's roots. 

Absorption of soluble plant food by soils. If the plant food 
made sohible by the chemical changes occurring in soils were not 



56 Agricultural Chemistry. 

retained by its absorptive power the depletion of fertility would 
go on at a much more rapid rate than it actually does. Most 
soils contain substances, which have the power of uniting with 
potassium, ammonium, and to a less extent with calcium com- 
pounds and with phosphates, converting them into insoluble 
forms. If a solution containing phosphoric acid, potash or am- 
monia is poured upon a sufficiently large quantity of fertile soil, 
the water which filters through will be found nearly destitute of 
these substances. This retentive power of a soil is of the great- 
est agricultural value as it enables it to maintain its fertility 
when washed by rain and permits of the economic use of many 
soluble manures. Ferric oxide, a common ingredient of soil and 
one to which the red color of many soils is due, will retain and 
fix any soluble phosphate. When a solution of phosphate of cal- 
cium in carbon dioxide is placed in contact with an excess of 
hydrated ferric oxide, the phosphoric acid is gradually absorbed 
and the calcium left in solution as a carbonate. Hydrated 
alumina acts in the same way. Ferric oxide and alumina have 
also a retentive power for ammonia, potash and other bases, but 
the compounds formed are more or less decomposed by water. 

The permanent retentive power of soils for potash and other 
bases is chiefly due to the hj^drous double silicates. 

Humus has a great absorptive power for ammonia. It also re- 
tains other bases with which it can form insoluble compounds. 

Magnesia, lime and soda are retained by the soil, but in a 
less powerful manner than are potash and ammonia. "When a 
solution of a salt of potassium or ammonium is placed in contact 
with a fertile soil, lime will come into solution and take the place 
of the potash or ammonia, which is by preference, absorbed. 

Soils destitute of lime retain very little potash or ammonia 
when these are applied as salts of powerful acids, as for instance, 
as chlorides, nitrates, or sulphates. When carbonate of calcium 
is present the potassium or ammonium salt is decomposed, the 
base is retained by the soil, while the acid escapes into the drain- 



The Soil. 57 

age water united with calcium. This is illustrated in the fol- 
lowing equation: 

Calcium carbonate + potassium chloride = calcium 
chloride -f- potassium carbonate. 
The addition of marl or limestone may thus greatly increase the 
retentive powder of a soil for bases. The bases absorbed by the 
soil may be slowly removed by the action of water. This of 
course occurs to the least degree in a soil that has absorbed little 
or has been already washed, and is greatest in a soil that has been 
heavily manured. 

The peiTaanent fertility of a soil is closely connected with its 
power of retaining plant food. In soils containing clay, only 
traces of phosphoric acid, ammonia or potash are ever found in 
the drainage water. Sandy soils, from their smaller chemical 
retentive power and free drainage, are of less natural fertility 
and much more dependent on immediate supplies of plant food. 

There can be little doubt that the active plant food contained 
in a soil, which is capable of being taken up by roots, exists 
either in solution or in the states of combination just referred 
to — that is, in union with ferric oxide, hydrous silicates or hu- 
mus. Different crops have very different powers of attacking 
these various forms of plant food. 

Nitrification. Perhaps the most important reactions going on 
in a soil are those connected with the decay of organic matter 
and the changes in the state of combination of the nitrogen. Th<; 
organic matter is continually being oxidized, the carbon being 
mainly converted into carbon dioxide. The material from which 
the nitrogenous matter of soils is derived contains always a large 
proportion of carbon. In the roots and stubble of cereal crops 
the relation of nitrogen to carbon is about 1 :43 ; in those of 
leguminous crops 1 :23 ; in moderately rotted farm manure 1 :18. 
In an aerated soil these materials are oxidized by the action of 
various organisms (worms, fungi, and bacteria) and large quan- 
tities of carbon dioxide produced. As a result of this loss of 
i^arbon, we find that the surface soil of a pasture (roots removed) 



58 Agricultural Chemistry. 

will contain about 1 part of nitrogen to 13 of carbon ; the snrfaeft 
soil of an arable field 1 :10, and a clay soil 1 :6. These figures 
represent the proportion of nitrogen to carbon in the commonest 
forms of humus matter. Humus represents merely a stage in 
the decomposition of organic matter; in the end the whole of 
the carbon, hydrogen and nitrogen appear as carbon dioxide, 
water and ammonia or nitrates. 

The nitrogen contained in humus is not in a condition to serve 
as food for ordinary crops. The gradual decomposition of soil 
humus is consequently generally essential to fertility. This 
change in the humus is brought about by fimgi and bacteria, 
which convert the nitrogen of organic matter into ammonia and 
nitrates, forms w^hich are soluble in water and available to the 
plant. The final nitrification of ammonia is performed by two 
species of bacteria, one of which produces nitrites, w'hich the 
other changes into nitrates. Fresh plant residues are more easily 
nitrified than old humus matter, but nitrification does not begin 
until the earlier stages of decomposition have occurred. 

The nitrifying organisms occur most abundantly in the surface 
soil; the depth to which their action extends depends on the 
porosity of the soil. In experiments at Rothamsted, England, 
on a clay subsoil, it was found that the organisms did not always 
occur in samples of the soil taken at more than 3 feet below the 
surface. 

Nitrification only takes place in a moist soil and one sufficiently 
porous to admit air. It is always necessary that some base 
should be present with which the nitric acid formed may com- 
bine. This condition is usually fulfilled by the presence of car- 
bonate of lime. Lack of oxygen and an acid condition of the 
soil are both unfavorable to the growth of nitrifying organisms. 
This gives us a rational explanation of the advantages of thor- 
ough tillage which aerates the soil and of the maintenance of 
non-acid soils by the application of lime. Nitrification is most 
active in the summer season ; it ceases near the freezing point. 
The nitrifying organisms may be killed by severe drought. 



The Soil 59 

The oxidation of humus not only makes the nitrogen, which 
it contains, available to plants, but it also liberates the ash con- 
stituents combined with the humus and enables them to take part 
again in the nourishment of the growing crop. 

Oxidation is most active in soils under tillage. In arable land 
the production of available plant food is at its maximum and 
so is also the waste by drainage. The nitrogenous humus matter 
of tilled laud is maintained only when the new supply from crop 
residues and organic manures is equal to the amount annually 
oxidized. In an untilled pasture or forest soil, on the other hand, 
a considerable accumulation of organic matter may take place, 
the annual residue of dead leaves and roots being often in excess 
of the amount oxidized. 

In a peat bog oxidation is further checked by the high water 
level, which excludes air from the soil ; under such conditions an 
unlimited accumulation of organic matter may take place if 
plants capable of growing under these circumstances are present. 

Dentrification — "When a soil is not in an aerated condition, 
but has the spaces between the particles filled with water, the- 
nitrates present are destroyed by certain kinds of bacteria, the 
oxygen of the nitrate combining wMh carbon to form carbon 
dioxide, while the nitrogen is set free and returned to the air 
in its elemental condition. If a soil be consolidated, water- 
logged or highly charged with oxidizable carbonaceous matter, 
the conditions become favorable for denitrification. Conditions 
favorable to nitrification, such as a plentiful supply of oxygen 
and absence of acidity, are those unfavorable to denitrification, 
so that the farmer in producing proper conditions for the former 
desirable process is at the same time preventing the injurious 
denitrification. The application of very large dressings of 
manure, along with nitrate of soda, sometimes causes a consid- 
erable loss of nitrogen from this process of denitrification.^ 

Fixation of atmospheric nitrogen in soils. Besides the organ- 
isms associated with leguminous plants and which assimilate- 
atmospheric nitrogen freely Avhen in union with the roots of thiv 



60 Agricultural Chemislry. 



n 



iiost plant, there are bacteria in the soil which use free nitrogen, 
but which do not grow in union with the higher plants. These 
bacteria are found in most soils and are said to possess this power 
when the supply of carbonaceous matter in the soil is plentiful. 
Indeed, some years ago, such organisms under the name of 
''alinite" were prepared for sale, but the success attending their 
use was doubtful and their manufacture has ceased. 

It is tliought that the fertility and richness in nitrogen of 
forest or prairie soil is largely due to the activity of such or- 
ganisms, which would find suitable conditions for growth in the 
large quantity of organic carbonaceous matter contained in such 
soils. At present it is impossible to say whether the nitrogen 
added to the soil in this way is of any considerable amount. 

Gases in a soil. The spaces between the particles of soil, be- 
sides containing a certain amount of moisture, are usually occu- 
pied by air. Because of the chemical changes going on in the 
soil this air becomes robbed of its oxygen, and enriched with 
carbon dioxide. This air is not stagnant but undergoes constant 
i-enewal by diffusion from the air above. 

The gases drawn from the soil at different times Avill be found 
to vary in composition ; the oxygen may be anywhere from 10 to 
20 per cent, the carbon dioxide from 1 to 10 per cent, while the 
nitrogen usually differs very little in amount from that in the 
atmosphere, that is, about 78 per cent. The amount of carbon 
dioxide is greater and of oxygen less during the summer and 
autumn than in the winter or spring. The higher temperature 
in the soil during summer and autumn favors chemical decom- 
l)osition. with greater production of carbon dioxide. 

Tillage and drainage. The operations of tillage and drainage 
serve in many important ways to make the conditions for plant 
life more favorable and to increase the amount of plant footl 
which is at the disposal of the crop. 

By tillage the surface soil is pulverized and brought into a 
loose, open condition. Large lumps are broken into small par- 
ticles and the fine tilth thus obtained, allows a rapid extension 



The Soil. Gl 

of the delicate root fibres and consequently g^reater room for root 
growth. It increases the surface to which the roots are exposed 
and necessarily gives the developing plant a larger feeding aren. 

Tillage hastens chemical changes in the soil by bringing to- 
gether particles which have not before been in contact. Par- 
ticles with different chemical properties are thus enabled to act 
apon each other. 

The changes induced by freezing and thawing may also be 
greatly increased by proper tillage. Fall plowing exposes the 
large lumps to the influence of the weather during the winter. 
This disintegrates the clods and improves some classes of soils 
in a remarkable manner. It also tends to save the moisture, as 
the loose ground turned up by the plow prevents loss of water 
by evaporation. The broken uneven surface also favors a greater 
absorption by the soil of the winter rain or snow. In an experi- 
ment at the "Wisconsin Station, a plot plowed in the fall con- 
tained 1.15 acre inches more water than an adjacent plot not 
so plowed. It must be remembered that fall plowing may not 
always be the best practice, as hard soils, low in humus, may be 
badly puddled if fall plowed. Plowing the ground very early in 
the spring is a rational practice, for there is no other season when 
tillage is so effective in conserving the soil moisture. Experi- 
ments indicate that in soils where such practice has been fol- 
lowed, the moisture content will be greater than in those un- 
plowed. Judgment must be exercised, however, in the choice 
of time in order that no injury to the texture may follow. 

By the action of the plow, the residues of crops, weeds and 
manures are buried, and incorporated with the soil. The deep 
tillage of heavy land allows rain to penetrate it and establishes 
the drainage of the surface soil, and increases the temperature. 

A shallow surface tillage preserves the moisture of the soil in 
time of drought. It lessens the evaporation from the surface by 
breaking the capillary connection with the store of water below 
the surface. After a rain this will be again established and 
the cultivation should be repeated as soon as possible. Such a 



G2 AgncuUural Chemistry. 

surface layer of dry soil is called an "earth mulch" and serves 
the same purpose as a covering of straw or like material. 

Another important result of tillage is that the soil is thorough- 
ly exposed to the influence of the air. The nitrification processes 
are greatly facilitated. Avith the production of nitrates and car- 
bon dioxide. The disintegration and solution of mineral par- 
ticles will take place from the mechanical and chemical actions 
brought into play. It will also prevent the formation of such 
compounds as sulphide of iron, known to be injurious to vege- 
tation. Oxygen is also necessary for the germination of seeds, 
and the aeration of soils by tillage is necessary for this important 
start in the plant's development. 

By means of tile drainage the many chemical reactions' going 
on in a soil are carried down to a greater or less extent into the 
subsoil; for as the water level is lowered the air enters from 
above to fill the spaces in the soil. By drainage, the depth to 
which the roots penetrate, and consequently the extent of their 
feeding ground, is increased. This helps them to withstand 
drought. They w^ill not be so easily affected by the extreme dry- 
ing of the surface of the soil that takes place in times of littU: 
rainfall. Roots vnll not grow in the absence of oxygen and will 
rot as soon as they reach a permanent water level. 

In a water-logged soil denitrification is active and nitrates 
present are destroyed, a part of the nitrogen being evolved a.s 
elemental nitrogen and returned to the atmosphere. The soil 
may in this way, suffer a considerable loss of plant food by lack 
of drainage. 

Losses caused by drainage. The water draining from land 
alwaj^s carries with it dissolved matter. The substances chiefly 
removed by the water will be calcium carbonate, and the nitrates, 
chlorides and sulphates of calcium and sodium. When heavj' 
rain falls these substances are washed into the subsoil and partly 
escape by the nearest outfall into the springs, brooks and rivers. 
The loss of nitrates during a wet season may be very consider- 



The Soil. 



63 



able. The loss is greatest from uneropped soil for several 
reasons : 

(1) Because of the greater amount of drainage. 

(2) Because no absorption of nitrates by the roots of plants 
takes place. 




Showing the dangeruua iJi.u Uit- oL allowing soils to remain bare and 
exposed to the washing of rains (after Vivian). 

(3) Because the land, when free from crops, dries more slowly 
alloAAang nitrification to proceed for a longer time. 

The average loss of nitrogen as nitrates from uneropped soil 
at Rothamsted, England, for 20 years, was 33.8 pounds per acre 
which is equal to 216 poiuids of commercial nitrate of soda. The 



6-1 . Agricultural Chemistry. 

loss will vary greatly with the nature of the soil. When the land 
is under crop this loss of nitrates by drainage is greatly reduced, 
these being constantly taken up by the roots and employed as 
plant food. In an experiment at Grignon, France, the yearly 
loss of nitrogen per acre on a soil bearing rye grass was but 
2.3 pounds. 

The losses of calcium carbonate vary considerably, dependent 
upon the nature of the soil. From soils of igneous origin its 
amount has been estimated at 500 pounds per acre per year, 
while from limestone soils the loss has been estimated at as much 
as 2700 pounds per acre. The amount lost is increased when 
ammonium compounds are used as fertilizer. 

The loss of phosphoric acid is probably very small, except in 
the case of peaty soils, which though often very deficient in this 
constituent generally lose much in the draina-ge. This is prob- 
ably due to the presence of vegetable acids and carbon dioxide 
produced by the decay of organic matter, which would intensify 
the solvent action of water. German experiments report an 
annual loss per acre of from about 8 poimds for clay soils to 
]9.() pounds for peaty soils. 

The loss of potash is variable, but small in amount. From ex- 
periments at Rothamsted, the annual losses in potash per acre 
were found to vary from 3 to 12 pounds. The losses of sulphur 
by drainage from soils may be considerable. At Rothamsted it 
was found that about 50 pounds per acre per year of sulphur, 
calculated as sulphur trioxide, escaped into the drainage water. 

Highly manured land will sustain larger absolute losses of 
plant food than lands in an average state of fertility. 

Soil as a source of plant food. The proportion of plant food 
present in soils is very small even when the soil is extremely 
fertile, the bulk of the soil serving as a support for the plant and 
as a sponge to hold the water. Many chemical analyses of soils 
have been made and these show a considerable variation in the 
composition of soil. A good arable loam may contain 0.15 per 
cent of total nitrogen, 0.15 per cent of total phosphoric acid, 



The Soil. 



65 



0.10 per cent of total sulphur trioxide, and 0.2 per cent of potash 
and 0.5 per cent of lime, soluble in hydrochloric acid. Much 
larger quantities may, of course, occasionally be present. Plant 
food is not equally distributed throughout a soil. If a soil is 
separated by sifting into finer and coarser particles, it will be 
found that the finer particles are much the richer in plant food. 

The weight of soil on an acre of land is so large that even 
small proportions of plant food may amount to very considerable 
quantities. An arable loam to the depth of 1 foot will weigh, 
Avhen perfectly dry, about 4,000,000 pounds. A pasture soil will 
be lighter, the first foot weighing when dried with the roots re- 
moved about 3,000,000 pounds. If such soils therefore contain, 
when dry, 0.10 per cent of nitrogen, phosphoric acid, potash or 
sulphur trioxide, the quantity of each in 1 foot of soil will be 
from 8,000 to 4,000 pounds per acre. 

The following table, partly taken from Vivian, gives the ap- 
proximate amounts of nitrogen, phosphoric acid, potash and sul- 
phur trioxide in the first foot of typical sandy loam, clay loam 
and clay soils : 



Amount of Plant Food per Acre in the Surface Foot. 



Kind of Soil 


Nitrogen 

lbs. 
per acre 


Phosphoric 

acid 

lbs. 

per acre 


Potash 

lbs. 
per acre 


Sulphur 
trioxide 

lbs. 
per acre 


Sandy loam 

Clav loam 

Clay 


.3, 736 
4,789 
3,250 


7,326 
4,935 
5,600 


28.669 
44,827 
12, 600 


4,000 (assumed) 
4,000 (assumed) 
4,U00 (assumed) 



The amount of plant food present in the soil is surprising, in 
view of the fact that it is often difficult to maintain a satisfactory 
yield of crops. An acre of soil may contain many thousand 
pounds of phosphoric acid or of nitrogen and yet be in poor con- 
dition; while an application of commercial fertilizer supplying 
50 pounds of readily available phosphoric acid in the form of 



66 AgricuUvral Chemistry. 



1 



super-phosphate or nitrogen as nitrate of sodium, may greatly 
increase its productiveness. If we compare the above table with 
the table in the appendix, showing the amount of plant food re- 
moved by various farm crops, it will be seen that the clay loam 
soils show the presence of sufficient nitrogen for 95 crops of 
wheat yielding 30 bushels per acre; phosphoric acid for 233 
crops ; sulphur trioxide for 254 crops ; and potash enough to sup- 
ply 1555 such crops. There is, in addition, nearly as much phos- 
phoric acid and potash in the second and third foot, so that as 
far as the latter substance is concerned, the supply seems almost 
inexhaustible. The other two substances, nitrogen and phos- 
phoric acid, and probably a third, sulphur, must be considered 
as limited in quantity in many of our soils. In peat soils, potash 
may also be very low. 

"While chemical analysis will often disclose a large total amount 
of plant food sufficient for many crops, nevertheless experience 
has demonstrated that long before the theoretical number of 
crops have been produced the yield will have decreased so mate- 
rially as to become vinprofitable. 

Available plant food. Chemical analysis gives the total 
amount of Jiitrogen, phosphoric acid and potash in a soil, but 
it does not indicate what part of these materials is available to 
the plant. It takes an inventory of our stock on hand but does 
not measure the crop-producing power of the soil. A large pro- 
portion of this plant food is locked up in insoluble compounds, in 
M"hich form the plant is unable to use it. Food can be taken uj) 
by the roots of plants only when in solution or in a condition 
capable of being dissolved by contact with the acid sap of the 
root hairs. 

The agencies operative in the soil and which we have already 
considered are continually changing these insoluble compounds 
to forms available to the plant; most of the soil ingredients are 
in an insoluble form and this fact is really of the greatest im- 
portance, for if it were not so soils would then lose fertility by 
heavy rains. The imavailable or ''potential" plant food is grad- 



The Soil 6Y 

ually being made available, but not with sufficient rapidity to 
replace that removed from the field at harvest, and the yield of 
crop produced will be limited by the element of this available 
plant food present in least quantity. 

Continuous cropping of the soil, with the removal of every- 
thing from the field results in the exhaustion of the plant food 
which has been rendered available during the past ages. 



CHAPTER IV 
NATURAL WATERS 

Pure Water — or the substance made of the two elements hyd- 
rogen and oxygen — practically never occurs in Nature. Because 
of its great solvent properties, water always dissolves certain 
quantities of every substance with which it comes in contact. 

The purest fonu of natural water is rain ; however, rain water 
is never pure, but contains varying quantities of dissolved mat- 
ter. The quantity of dissolved substances will depend upon the 
locality in which the rain fell. In cities and in the neighborhood 
of factories this will be larger than in the open country. The 
character of the substances in solution will also depend upon the 
locality. The rain water in cities, besides containing compounds 
of nitrogen, as ammonium nitrate, may be acid. This is due to 
dissolved sulphuric acid, which had its origin in the sulphur di- 
oxide produced from burning coal. In addition to these sub- 
stances rain water contains dissolved gases. 

"When it reaches the earth the water at once begins to dissolve 
the substances upon which it falls. In regions where the surface 
is composed of hard, igneous rocks, the quantity of material dis- 
solved is small, while on lime-stone soils the amount of calcium 
carbonate that goes into solution is large. 

The water which drains away from a soil, partly finds its way 
into the nearest creek, then to a stream or river, and finally to 
the sea. Another portion sinks into the earth, until stopped by 
some impervious layer of rock — as shale or hard pan — when it 
accumulates and eventually finds an outlet at some lower level 
in the form of a spring. 

The industrially important waters may be classed as follows': 

1. Rain tvater. 

2. Ground waters furnished by 

(a) Springs, 



Natural Waters. 69 

(bi Shallow wells (penetrating but one geological stra- 
tum) , 

(c) Deep wells (passing through more than one such 
stratum) , 

3. Surface waters consisting of 

(a) Flowing waters (streams). 

(b) Still water (ponds, lakes, etc.) 

4. Sea water. 

Rain water. The composition and character of this has al- 
ready been described in Chapter II. It contains very little min- 
eral matter and is described as "soft" for this very reason. If it 
could be collected without further contamination it would be by 
far the best for most purposes. The acidity of the rain in dis- 
tricts where much coal is burned is of great importance as affect- 
ing the growth of plants, particularly grasses and certain trees. 
In addition to its direct injurious effect upon the foliage, it 
exerts a deleterious action upon the soil, tending to remove the 
calcium carbonate or other basic material and to promote "sour- 
ness," a condition which is very unfavorable to the growth of 
most useful plants. It is kno\^^l that grass lands under such 
circumstances become almost sterile, the last plants to succumb 
to the unfavorable conditions being usually the "sorrel" or 
"sweet dock." 

Ground Water. The water issuing from springs varies great- 
ly in the amount and nature of the dissolved matter which it con- 
tains. If this be small, and not possessed of strong odor or taste, 
the water is described as fresh water ; but if a large quantity of 
dissolved matter be present, or if the water possesses pronounced 
taste, odor, or medicinal properties, it is known as a mineral 
water. 

Many spring waters contain the following substances, but in 
varying amounts : 

1. Calcium and magnesium carbonates dissolved in excess 
of carbon dioxide. 

2. Calcium or magnesium sulphate. 



70 Agricultural Chemistry. 



3. Sodium or potassium chloride. 

4. Alkaline silicates. 

5. Dissolved gases as oxygen, nitrogen and especially carbon 
dioxide. 

Calcium and magnesiiun carbonates are almost insoluble in 
water, but if the water contains carbon dioxide, the readily sol- 
uble bi-carbonates of calcium and magnesium are formed. 

Such action occurs in all lime-stone districts and the removal 
of the rock by solution gives rise to the caves and underground 
water courses so common in such localities. The great Mammoth 
Cave of Kentucky and Perry Cave of Northern Ohio are illus- 
trations of such action. 

When such water is boiled the bi-carbonates are decomposed, 
losing part of their carbon dioxide, and normal carbonates are 
again formed. These are insoluble and consetjuently appear as 
a precipitate. In many cases the precipitated calcium or mag- 
nesium carbonate forms a firmly adherent coating or crust upon 
Iho bottom or sides of the kettle or boiler. 

Calcium and magnesium sulphates are soluble in water, the 
former to the extent of about 1.7 grams per liter (1 oz. in 18 
(quarts of water). "Waters containing calcium or magnesium 
compounds are known as "hard." waters, and have a peculiar 
and well known action on soap. The latter is essentially a sodium 
salt of the fatty acids, as stearic, palmitic and oleic acids. These 
acids are the constituents of our principal fats and it is the com- 
mon practice of every good housewife to save the fat "scraps" 
for the home soap-making. The sodium and potassium salts of 
the fatty acids are soluble in water, but the calcium and mag- 
nesium salts are insoluble. For water to form a lather with 
soap or properly exercise its cleansing power, it is necessary that 
the water should contain in solution some of the sodium or potas- 
sium salts of the fatty acids. When a small quantity of soap is 
dissolved in hard water, the calcium or magnesium present in 
the water displaces the sodiiun or potassium and gives a curdy, 
flocculent precipitate of the calcium or magnesium salts of the 



1 



Natural Waters. 71 

fatty acids. The dissolved soap is thus removed and more has 
to be dissolved before the proper cleansing action can be exerted. 
Hence hard waters are unsuitable for domestic, especially for 
laundry, purposes ; they involve the consumption of large quan- 
tities of soap and contaminate the washed articles with the pre- 
cipitated "lime" or "magnesia soap." 

Hard waters are also unsuitable for steam-raising, since the 
deposit of calcium carbonate or calcium sulphate (boiler scale) 
upon the boiler plates greatly increases the consumption of fuel 
required for the production of a certain quantity of steam. Cal- 
cium carbonate alone forms a porous and non-adherent scale, 
which is easily removed by "blowing off" the boiler. Calcium 
sulphate forms a hard compact scale, which adheres very firmly. 

A distinction is often made between waters, which contain 
their calcium and magnesium as bi-carbonates and those in which 
the salts present are as sulphates. The former are known as 
"temporarily" the latter as "permanently" hard waters. By 
the removal of the excess of carbon dioxide from the former the 
calcium and magnesium carbonates are precipitated, while with 
the latter the salts are in solution and cannot be precipitated by 
the simple removal of carbon dioxide. 

The usual method of procedure to effect the softening of tem- 
porarily hard water is to add "milk of lime" in sufficient quan- 
tity to combine with the free carbon dioxide and that present as 
bi-carbonates. The precipitate formed will be found to contain 
the calcium and magnesium carbonates originally present, to- 
gether with that formed from the added lime. On standing, the 
precipitate settles out and the clear liquid is then almost free 
from calcium and magnesium and is "soft." The milk of lime 
should be added slowly and gradually and care be taken that no 
great excess is used. Water so treated is much improved both 
for washing and for steam-raising purposes. The "milk of 
lime" is made by treating a quantity of quick lime with water 
and after thoroughly stirring, the "milk" is then mixed with the 
water to be purified. 



72 Agricultural Chemistry. 



% 



Another method is to boil the water either in the open air or 
in special heaters. This decomposes the bi-carbonates, drives 
out the excess of carbon dioxide and the normal carbonates of 
magnesium and calcium settle out as precipitates. 

Permanent hardness is less easily remedied, for in every case 
the treatment of the water leaves in solution some substance more 
or less deleterious. Sodium carbonate and barium chloride are 
the materials in common use. A recent suggestion calls for the 
use of sodium bi-chromate within the boiler, as a corrective for 
both temporary and permanent hardness. It is claimed that the 
calcium and magnesium ehromates precipitate in the boiler as a 
loose, non-adherent mass, which is removed by "blowing off" 
daily. Tt is further claimed that the free chromic acid does not 
attack the boiler iron. Much care is necessary in order to avoid 
an excess of any chemical added. As a rule the water should 
be treated before it goes into the boiler. But if the scale-forming 
material does not exceed 150 parts per million, the purification 
may be done in the boiler itself, followed by daily "blowing off." 

A great many proprietary "anti-scale" preparations are sold, 
many of which are of no particular value. Most of them are to 
be used inside the boilers. Some are supposed to act chemically 
on the impurities and others are mechanical, preventing the ad- 
herence of scale. The former usually contain soda-ash, caustic 
soda, barium hydroxide, or sodium phosphate. Tannin in the 
form of sodium tannate, is sometimes employed, by which the 
calcium and magnesium are separated as tannates. 

In a drinking water the presence of calcium compoimds, except 
perhaps in excessive amounts, is not objectionable. Indeed, it is 
often advantageous, furnishing a portion of the lime necessary 
for the building up of the hard parts, such as bones or shells, of 
the animal. Moreover, in many cases water is delivered through 
lead pipes and soft waters, especially if they contain vegetable 
acids, as for example peaty watei*s, attack and dissolve the lead, 
and often to such an extent as to cause lead poisoning in those 



Natural Waters. 73 

who drink them. The presence of calcium sulphate renders wa- 
ter incapable of this dangerous action upon the lead. In the 
presence of calcium sulphate the metal becomes coated with a 
film of the very insoluble lead sulphate, which protects it from 
further contact with the water. 

Organic matter. Of greater importance than the mineral mat- 
ter in drinking water, is the amount and nature of the organic 
matter. This in itself is comparatively harmless. Its import- 
ance lies in the influence it may have upon the kinds of micro- 
organisms which accompany it. Animal excreta is the most dan- 
gerous contamination, since the micro-organisms which cause 
various diseases, as for example, typhoid, cholera, etc., are liable 
to be thus introduced into the water. Animal organic matter is 
richer in nitrogen than most vegetable refuse, so that in practice 
the detection of much combined nitrogen, whether as organic 
matter, ammonium salts, or nitrates, is regarded as sufficient to 
indicate that the water has been contaminated with sewage or 
other animal matter. If much organic matter of animal origin 
be present there must always be considerable risk of disease pro- 
ducing organisms finding their way into the bodies of those who 
drink it ; and though such contaminated water may be, and often 
is, drunk for years with impunity, its consumption is decidedly 
dangerous. 

Another substance characteristic of sewage is common salt; 
consequently the presence of much chlorine in a water is gen- 
erally indicative of sewage contamination, unless the water is 
derived from some rock which contains salt, or is collected near 
the sea. 

What has been said has an important bearing upon the loca- 
tion of the farm wells. Dangers of seepage from the out door 
privy and the barn-yard must be avoided by locating the well 
at a proper distance from both and on higher ground. Even 
these precautions may not always entirely remove the danger of 
contamination. 



74 



AgricuUiiral Chemistry. 



Analyses, quoted from Ingle, of typically good and bad drink- 
ing waters, are given below. 

Composition of Good and Bad Drinking Waters. 



Constituents 


Good water 
Parts per million 


Bad water 
Parts per million 


Total solids 


63 
0.25 
03 
0.07 

11. 4 
1.4 

34.3 

35.7 




530 


Nitrogen an nitrites ami nitrates 

Free ammonia 


7.8 
4.3 


Albuminoid ammonia 


0.9 


Chlorine 


69 


Tern, hardness 


102.9 


Per. hardness 


205.9 


Total hardness. 


308 8 







By hardness is meant the parts of calcium carbonate equivalent 
to the total amount of calcium and magnesium salts present in 
one million parts of the water. 

By albuminoid ammonia in the above table is meant the quan- 
tity of ammonia, which is evolved from the water by the decom- 
position of organic nitrogenous substances when distilled with 
an alkaline solution of potassium permanganate. 

Surface water. Rivers, ponds and lakes belong to this class. 
Most rivers originate in springs, so at first their water resembles 
that of their source. A considerable influx of surface water, 
however, generally enters the river and alters its composition. 
The composition of the waters of ponds or lakes will be much like 
that of the creeks and rivers flowing into them. The surface 
water usually contains less dissolved matter than spring water, 
but often more organic matter and suspended particles. The 
composition of the river water depends greatly upon the char- 
acter of the rocks from which it is collected. When the surface 
consists of igneous rocks or of sandstone, the water is usually 
soft, while in lime stone districts it will be hard. Some rivers, 
as for example the Trent of England, are rich in calcium sul- 
phate and to this fact the excellence of the Burton ales has been 



il 



Natural Waters. 



ascribed. The remarkable softness of the river Dee, which flows 
through the granite district of Aberdeenshire, England, has also 
received special notice. 

The following table represents the average composition of sev- 
eral well known lake waters of Wisconsin. 

Composition of Wisconsin Lake Waters. 





Parts per Million 




Lake Mendota 1 North Lake 


Devil's Lake 


Silica 


1.1 

0.8 

40.1 

42.3 

10.3 

2.0 


3.0 

0.6 

66.2 

46 4 

11.1 

4.0 


2.2 


Alumina and Iron 

Lime 


0.6 
4.5 


Matinesia 


1 .8 


Sulphur trioxide 

Chlorine 


6.7 

8.2 







The softness of the water of Devil 's lake is also to be attributed 
to the fact that it is located in a sandstone country. 

River water rarely contains large quantities of calcium car- 
bonate such as occur in some springs, since, owing to the free 
contact with air it never retains very large quantities of dissolved 
carbon dioxide. Calcium sulphate in river water is usually ac- 
companied by sodium chloride and magnesium salts. 

In thickly populated and manufacturing centers the rivers are 
contaminated with the sewage and trade effluent of the towns 
and villages, and thus often become foul and bad-smelling. This 
is to be deplored both on account of the annoyance and injury 
to health which they cause, and also because of the serious loss 
to the community of the valuable combined nitrogen and other 
manurial constituents contained in the sewage. It is estimated 
that the Mississippi river carries daily to the sea 50 to 100 tons of 
nitrogen as nitrates. In some cities of America, as well as in 
Europe, the sewage is pumped directly to nearby lands called 
"sewage farms." where it is allowed to run at intervals between 



76 Agricultural Chemistry. 

thrown-up earth ridges. On these ridges various crops, especially 
vegetables, are grown, with the resultant utilization of the 
nianiirial constituents of the sewage. 

The amount of suspended matter in river water varies enor- 
mously, depending upon the rain fall, the character of the sur- 
rounding soil, and other circumstances. Soft waters or those con- 
taining carbonate of soda, are often muddy, while hard waters 
tend to deposit their suspended clay and become clear. In some 
cases the quantity of suspended matter is very great, and a dense 
muddy river, if it over-flows its banks, deposits upon the soil 
a layer of finely divided particles of materials brought down 
from higher up the valley. The sediment is often rich in plant 
food and forms an important fertilizer. In some places in Eng- 
land, land is systematically treated with the flood water in order 
to increase the thickness of the soil. The process is IcnoT^n as 
''warping" and the "warp" soils are extremely rich and fertile. 
The Nile river in Egypt affords, on a large scale, a still better 
example of a river used in this manner. 

In countries of limited or unevenly distributed rainfall, as in 
many of our western states, irrigation is often practiced. In 
this case, since there is very little drainage, the composition of 
the water used is of importance. If the water is charged with 
common salt, sodium sulphate or sodium carbonate, there is grave 
danger of the surface soil, through the prolonged evaporation 
and concentration of the water, becoming charged with the sol- 
uble matter to such an extent as to seriously interfere with plant 
growth. The soil is then said to become "alkali." This con- 
dition may also arise from accumulation-in-place of the salts, 
produced by the weathering of the rocks. The slight rain fall is 
insufficient to produce percolation through the soil and carry 
tlie accumulating salts into the under ground water system. This 
produces 9 sterile condition which may be caused by sodium 
sulphate and chloride (white alkali), or by sodium carbonate 
(black alkali). 



f 



Natural ^¥aters. 



77 



Different crops are possessed of different resisting powers to 
these salts. As a rule sodium carbonate is the most effective in 
causing injury to plants and sodium sulphate the least. For- 
tunately, however, "black alkali" — i. e., sodium carbonate — can 
be rendered almost harmless by the application of gypsum to the 
soil, which decomposes the sodium carbonate with formation of 
the very much less harmful substances, sodium sulphate and 
calcium carbonate. If "white alkali" is due to conmion salt, it 
cannot be cured except by drainage. 

According to results accumulated in this country, and tabu- 
lated by Ingle, the following figures give the highest proportion 
of sodium chloride, sodium sulphate and sodium carbonate which 
may be present in soils without injury to the plants named. The 
figures represent the amounts in pounds of the various constit- 
uents present in the upper four feet of soil per acre : 



Plant 



Sodium 
Chloride 



Sodium 
Sulphate 



Sodium 
Carbi)nate 



Grape 

Fig 

Orange 

Apple. . . . .' 

Peach 

Oriental sycamore 

Salt hu^h 

Alfalfa, old 

Sugar beet 

Ridish 

Wheat 

Barley 

Sorghum 



800 
9, 640 
3,360 
1,240 
1,000 
20, 320 
12, 520 
5, 760 
5,440 
2,240 
1,160 
5, 100 
9,680 



40, 800 

24, 480 

18,000 

14,240 

9, 600 

19,240 

125,640 

K'2,480 

52, 640 

51,880 

15,120 

12,020 

61,840 



7,550 
1,120 
3,840 
640 
680 
3, 200 

18,560 
2.360 
4,000 
8,720 
1,480 

12,170 
9,840 



In this table it is assumed that the weight of soil to a depth 
of four feet per acre is 16,000,000 pounds, or that each acre-foot 
of soil weighs 4,000,000 poimds. One per cent of any constituent 
would then correspond to 40,000 pounds per acre to a depth of 
one foot, one-tenth per cent to 4,000 pounds, and so on. 



78 



Agricultural Chemistry. 



Sea water varies in composition, dependent upon the locality 
at which it is taken. Its composition is affected by the influx 
of fresh water from large rivers, etc., but far out from land it 
is very constant in composition. The average amount of total 
solid matter is about 34,000 parts per million. Thorpe, in 1870, 
found in the water of the Irish sea the following constituents 
expressed in parts per million: 



Sodium chloride 26,439 

Potassiurn chloride 746 

Magnesium chloride 3,150 

Magnesium bromide 71 

Magnesium sulphate 2,060 

Magnesium carbonate Trace 



Magnesium nitrate 2 

Calcium sulphate 1,332 

Ca,lcium carbonate 48 

Ammonium chloride 04 

Ferrous carbonate f) 

Silicic acid Trace 



In certain lakes having no connection with the ocean, the con- 
centration of the water becomes much greater, and the total solid 
matter may reach even seven or eight times that found in the 
ocean. Examples of such water are found in the Dead Sea and 
the Great Salt Lake of Utah. 



II 



CHAPTER V 
THE PLANT 

The growth of plants is the result of a series of chemical 
changes which first assume prominence in the sprouting seed, 
with the ultimate object of producing seed for a succeeding gen- 
eration. The effects of these changes become inconspicuous in 
resting seeds, but their activity ceases only with the death of the 
organism. 

Germination. A seed is essentially an embryonic plant sur- 
rounded and protected by a supply of reserve materials which 
serve as food until the young plant can forage for itself. These 
reserve compounds are more or less complex structures involving 
simple plant-food constituents derived from the air and soil. 
The changes by which they are altered for the use of the seedling 
are produced by sensitive compounds known as enzymes. 

These compounds are not endowed with life, but they are 
probably closelj' related in composition to the complex, nitro- 
genous compounds known as proteins, which form the basis 
of living matter, and with whose chemical changes the life pro- 
cesses of plants and animals appear to be very closely connected. 
The exact nature of enzyme action is not knoMoi. One of the 
older and more prominent theories of this action was based upon 
the sensitiveness of these bodies and their proneness to undergo 
decomposition. It attributed their effects to a sympathetic rela- 
tion whereby they induced instability, or accentuated conditions 
already unstable, in certain other compounds and caused them 
to break down. This theory is insufficient for we now know that 
enzymes can effect the construction, as well as the destruction, of 
some compounds. Under proper conditions of temperature and 
moisture small amounts of a given enzyme induce changes in a 
large amount of matter, each kind of enzyme acting upon a 
specific compound or group of compounds. Thus, a specific type 



80 Agricultural Chemistry. 

of enzymes, designated as proteolytic in nature, alters the protein 
compounds of the germinating seed ; an enzyme known as diastase 
converts starch to dextrines and sugar; a lipase or fat splitting 
enzyme alters fats only, while still another type of enzyme lib- 
erates phosphorus, calcium and other ash constituents from or- 
gionic compounds of the seed. Phytase, which occurs in wheat 
and other grains, is an example of the last mentioned class of 
enzymes. It breaks up the compound known as phytin, produc- 
ing simple soluble compounds of calcium, magnesium, potassium 
and phosphorus. 

Consideration of this specific relation between enzymes and 
organic compounds and extension of our knowledge concerning 
the chemical structure of the substances involved therein have 
led to a theory which likens the action of an enzyme to that 
of a key upon a lock, in the sense that each key fits and trips 
only the particular lock to which it is adapted. This is more 
complete than the older theory, for it ascribes to the enzyme 
power to reconstruct its specific compound just as the key can 
lock as well as unlock. It is in harmony with the kuo\\Ti re- 
versibility of some enzyme actions. 

The fragments of compounds resulting from enzymatic action 
in the seed, combine with the oxygen of the air, always required 
for germination, and either yield energy for the growth of the 
young plant, or pass as soluble compounds with the sap into the 
growing seedling, there to be reconstructed into compounds form- 
ing the tissues of the young plant. 

By the time the reserve compounds of the seed are exhausted 
the young plant is differentiated into separate organs, known as 
ro-ot, stem and leaf, by means of which it can assimilate raw food 
materials from the air and soil. 

Functions of the root. The root is an organ of great impor- 
tance in the assiinilalion of food. Large amounts of water re- 
quired by the growing plant, are taken from the soil by means 
of the root and it is through this means that the plant obtains 
its nitrogen and ash constituents. 



The Plant 



81 



The activity of this organ in this connection is shown by the 
following figures quoted from King. The table expresses the 
pounds of water required to produce 1 pound of dry substance in 
the plant. 

Pounds of Water Required to Produce One Pound of Dry Substance. 

Kind of Plant Pounds of Water 

Dent Corn 309.8 

Barley 392.9 

Oats 522.4 

Red Clover 452.8 

Field Peas 477.4 

Potatoes 422.7 

When we consider that field crops require an amount of water 
from three hundred to five hundred times as great as their own 
dry weight, and that all of their nitrogen (except in the ease of 
leguminous plants) and all of their ash constituents are derived 
from the soil with this supply of water, the great importance of 




Showing the power of the rutabaga to obtain its phosphorus from insol- 
uble phosphates. 

Box. 1. Soluble phosphoric acid. 
P>ox 2. Insoluble phosphoric acid — Florida rock. 
Box 3. Insoluble phosphates of iron and aluminum. 
Box 4. No phosphate added. 



82 



Agricultural Chemistry. 



the function of assimilation performed by the roots becomes 
evident. 

"While some plants, as for example, tobacco and the potato, re- 
quire liberal supplies of plant food in readily available form, 
others, especially the cruciferae (turnip, rutabaga and related 
plants) and some of the gramineae (cereal grains and grasses), 
display marked ability to attack resistant compounds in the soil 
and obtain food from them. This difference is well illustrated 
by the following data obtained by Merrill at the Maine Experi- 
ment Station in studying the availability of phosphorus, when 
supplied in various forms to different crops. Other requirements 
of the plants than that for phosphorus were amply supplied. 
The figures express the percentage yield of diy matter, the yield 
with no phosphorus being taken as 100 per cent: 



Plant Family 


Crop 


No 
Phos- 
phorus 


Phos- 
phorus 
in ground 
Florida 
ruck 


Phos- Phos- 
phorus phorus 
in iron and in water 
aluniimini soluble 
phosphate! lorms 


Leguniinosae 

Graminae 

Solonaceae 

Cruciferae 


Peas 

Clover 

Barley 

Corn 

Potato 

Tomato — 

Turnip 

Rutabaga . . . 


Per cent 
100 
100 
100 
100 
100 
100 
100 
100 


Per (;ent 
140.4 
205.1 
117.7 
278.6 
114.1 
2.-15.7 
159.0 
2S6.0 


• Per cent 
108.6 
152.4 
128.1 
316.6 
121.6 
218.8 
204.2 
216.6 


Per cent 
191.8 
262.2 
232.5 
704.2 
lf>1.2 
376.1 
226.6 
378.1 



These data show a widely variant poM'er on the part of plants 
to assimilate comparatively insoluble and unavailable compounds 
of phosphorus. The great superiority of corn over barley and 
of the tomato over the potato in utilizing the insoluble phosphates 
is interesting as a demonstration that assimilating power is not 
uniform for membere of a plant family, but is a characteristic 
of the individual species. The cruciferae, however, as a family. 



The Plant. 83 

are notably efficient as phosphorus gatherers, while the grass 
family is characterized by high assimilation of silicon. 

The well laio\^Ti power of roots to etch the surface of lime- 
stone is due to excretion of carbon dioxide from this organ of the 
plant, and differences in ability to assimilate food materials may 
be explained partly by differences in carbon dioxide output. 

If the stem of an actively growing plant be severed at its junc- 
tion with the root and replaced by a pressure gauge, it will be 
found that the root exerts an upward pressure amounting in some 
cases to more than 30 pounds per square inch. According to 
Wieler this pressure has been found sufficient to support a column 
of water of the following heights in the plants indicated : 

Height of tcater column 
Plant supported by root pressure 

White Mulberry 6.5 inches 

European Ash 11.4 " 

Castor Oil Plant 181 .3 " 

Stinging Nettle 249.7 

Wine Grape 581 . 6 " 

White Birch 755.0 

Sweet Birch (Black Birch) 1043.2 

By this so-called ' ' root pressure ' ' the root is believed to func- 
tion in the movement of water through the plant. 

In biennial root crops such as the beet, the root of the first 
year's growth serves as a magazine for food from which the 
second year's growth is re-inforced for the production of seed. 
This reinforcing material is usually starch or sugar, with small 
amounts of nitrogen compoimds and ash constituents. 

The stem. The active portion of the stems of plants consists 
essentially of a system of tubes formed by continuously connected 
cells. These tubes serve as channels for the transportation of 
water and food materials and are surrounded by protecting and 
supporting tissue. In the stems of endogenous plants, as in the 
corn and the bamboo, the tough, smooth bark is formed by ag- 
gregates of the dead remains of conducting cells and newer 
growths are added by increments of these cells in the soft pith 



84 Agricultural Chemistry. 

toward the center of the stem. Groups of these cells, which 
traverse the pith of the stalk longitudinally, are familiarly known 
as the fiber of hemp and the threads of the corn stalk. The 
stems of exogenous plants like the oak and maple, which produce 
new tissue outward from a compact, central heart-wood, consist 
of a tough, supportive core of the older and denser tissue sur- 
rounded by the growing cambium layer. This whole structure is 
surrounded and protected by a layer of dead cells forming the 
outer bark. Sap is conveyed about these plants through channels 
in the cambium layer or inner bark, and may be obtained in 
quantity from some trees, as from the sugar-maple, by tapping 
into the inner bark and contiguous woodj'^ tissue in early spring, 
when the rapidly developing buds are drawing upon reserve food 
supplies in the trunk. In the case of the maple tree, starch and 
other reserve carbohydrates are in process of transportation to 
the buds in the form of sugars which may be recovered as such 
by concentrating the sap. 

The stems of some plants have the appearance of roots from 
the fact that they exist below the surface of the soil. The pods 
of the peanut, for example, ripen in the ground because the flower 
stems lengthen and penetrate the soil as soon as the blossom falls. 

Root stocks or rhizomes are subterranean stems, each joint or 
node of which puts out both leaf buds and roots. Each node is 
thus equipped to become an independent plant as soon as it is 
isolated from the parent stem. It is to this fact that the ex- 
treme troublesomeness of quack grass is due. Cultivation, ex- 
cept in a favorable season of prolonged drought, serves to in- 
crease the pest. Asparagus is another example of a plant grow- 
ing from a rhizome and well illustrates the function of the stem 
as a food magazine. 

Tubers are fleshy enlargements of the tips of subterranean 
stems. Their "eyes" mark the position of buds, which distin- 
guish them from true roots. p]ach of these eyes is the precursor 
of one or more new plants. The tubers of the potato, arrow 
root, and some other plants, are of great value as food because 



The Plant. 85 

of their high starch content. In these cases the stems serve as 
storage places for reserves of plant food. The bulbs of the onion, 
lily and other plants, are permanent buds, formed of fleshy, 
closely packed scales. They are properly a part of the stem of 
the plant, serving as reserve material for growth. The fleshy 
portion of the crocus, gladiolus and some other plants is not a 
bulb, but is an enlargement of the base of the stem. 

The stem also serves as a means of support for the leaves and 
fruit, favoring the exposure of both to the air and sunlight, es- 
sential to the chemical processes which promote growth. 

The leaf. The leaf is the seat of greatest constructive activity 
in the plant. The important process of transpiration, or escape 
of water from the plant, is controlled by minute openings upon 
the plant's surface. These openings, known as stomata, occur 
in small numbers upon the stems of plants, but they are most 
abundant upon the leaves. They are especially numerous upon 
the protected under surface of leaves, where, as in the case of the 
cabbage or apple, their number may reach 200,000 per square 
inch. The outlet of a stoma is lined by two peculiar cells which 
face each other, forming a miniature mouth opening outward 
from the surface of the leaf. These cells, called guard cells, are 
the seat of control in the action of the stomata. When the water 
supply is abundant and the plant cells are turgid, the guard cells 
are elongated vertically to the leaf surface and contracted par- 
allel to it, thus drawing apart and exposing an outlet for the 
evaporation of water. On the other hand, when the water sup- 
ply is limited and the plant cells wilt or shrink, the guard cells 
flatten and become elongated parallel to the leaf surface,, thus 
automatically closing the stomata and checking evaporation from 
the plant. This process partly controls the supplying of plant 
food from the soil and is an important means of maintaining 
optimum temperatures in the plant as a result of increased or 
decreased evaporation of water. 

The leaf inhales air through the stomata. From this supply 
of air it assimilates carbon dioxide for the construction of plant 



SQ Agricultural Chemistry. 

compounds and employs oxygen in the process of respiration ana- 
logons to that of animals. 

The magnitude of the former process can be realized when W(^ 
recall that a 12 ton crop of corn requires for its production four 
tons of carbon dioxide. To secure this amount, the plants must 
respire 10,000 tons of air or approximately one-fourth of the 
total amount over an acre of land. 

The construction of organic compounds, which is a character- 
istic function of the plant occurs principally in the leaf. It is 
initiated by the green coloring matter known as chlorophyll. 
This substance has been shown to be a specific but complex chem- 
ical compound. It may be seen under the microscope as granules 
clustered within the cells of all green plant tissues. In some 
colorless fungi and lower plants it is lacking. Such plants do 
not construct organic compounds independently but derive them 
from previously existing vegetation. The green color of plants 
is due to chlorophyll, as may be shown by extracting it witli 
alcohol. Such an extract is intense green in color, due to the 
chlorophyll removed by the alcohol, while the extracted tissue is 
bleached and colorless. In some unexplained manner this sen- 
sitive compound, under the influence of light, induces the union 
of carbon dioxide assimilated from the air, and water conveyed 
from the root, with the production of the first carbohydrates of 
the plant. 

It is not kno^vn whether this first product is starch, sugar, or 
a simple precursor of these compounds. The process involves 
the elimination of two parts of oxygon for each part of carbon 
dioxide assimilated, as shown by the following general expres- 
sion: — Carbon dioxide + "Water = Carbohydrate (Dextrose) 
+ Oxygen. 

The evolution of oxygen in this process has been proved by ex- 
periments in which living leaves were confined in inverted jars 
of water. A gas Avhich collected above the water responded to 
tests for oxygen and its volume was found to be equivalent to the 
carbon dioxide taken \\\). The plant also performs through the 



Jl 



The Plant. 87 

leaves the process of respiration or breathing, in which oxygen 
of the inspired air combines with compounds of the plant, with 
an accompanying elimination of carbon dioxide. This process 
is most evident in darkness since it is not masked then by the 
more extensive process of carbon dioxide assimilation. By com- 
bining the carbohydrates as a basal material with nitrogen and 
sulphur brought from the soil, the leaf cells produce a further 
class of organic compounds known as proteins. Nitrogen and 
sulphur usually enter the plant as highly oxidized compoimds 
and are built into the proteins after suffering reduction or loss of 
oxygen. 

The leaf functions also as a temporary reservoir for migratory 
compounds which, at the death of this organ, return into the 
general circulation of food materials in the plant. This is true 
particularly of trees and other perennial plants, whose dead 
leaves are skeletons consisting chiefly of cellulose compounds and 
unessential ash constituents like silica, the more important nu- 
trient compounds and ash materials having returned to the stem 
of the plant. 

Flowers, fruits, and seeds are pre-eminently seats of construc- 
tive processes in which chemical reactions are especially active 
and significant. Fragmentary protein structures, possibly the 
amino-acids, are here withdrawn from solution in the sap cur- 
rent and retained as finished proteins. Soluble carbohydrates 
are converted to starch or to some of the fats, which are present 
in the seeds. Ash constituents for the young plant of the next 
generation are stored away as constituents of organic compounds. 
Absorption of oxygen is especially marked in these organs and 
may be accompanied by considerable heat production. In the 
case of the Italian arum lily it has been observed that the large 
l)istil absorbs in one hour nearly 30 times its volume of oxygen 
with a resultant temperature of over 100° Pahr. 

The end of all this activity is the production of mature seed 
containing a finished plant embryo, a store of food materials, and 
enzymes to inaugurate the process of germination. At this stage 



88 Agricultural Chemistry. 

of growth, the leaves, stems and roots are contributing their re- 
serves for the production of seed. Migration of food constituents, 
especially of starch, nitrogen compounds and ash constituents, 
from the root or leaves now assumes prominence. While the ash 
constituents accumulate in the seed only in small amounts, 
sufficient for the g-rowth of a vi<>'orous seedling, some of the 
organic reserve compounds may be stored in excess, giving dis- 
tinctive character to the seed. This is true of starch, which gives 
the cereal grains peculiar value for the manufacture of foodstuffs 
and of alcoholic products. It is also tnie of fats and proteins, 
which give to cotton and flaxseed high coinmercial values as 
sources of oils and as protein-furnishing constituents of rations 
for live stock. Starch and fat serve the young seedling as 
sources of energy for growth and as material for carbohydrate 
construction until it becomes independent of the seed ; the pro- 
teins of the seed furnish simple nitrogenous structures from 
which the proteins of the seedling are formed. 

Compounds of the plant. x\s a result of the activity of the 
various plant organs, there is produced a great variety of com- 
pounds, partly transitory in nature and partly of permanent 
character. The following classification is a brief plan of division 
for the compounds of the plant : 

r Carbohydrates 
Water , Non- J Fats and waxes 

(Nitrogenous | Terpenes and essential oils 
,^ . \ lOrganic acids 

Organic or com- J 
bustible matter J [Proteins 

Amino-acids 
Amides 

lAmines and alkaloids 
Ash containing j Salts of organic acids 
compounds ( Inorganic compounds 

Water holds a place in the chemistry of the plant the import- 
Jince of which can hardly be realized. Besides its physical func- 
tions of transporting food materials and regulating the tempera- 
ture of the plant, it is responsible for maintaining the turgidity 
of the individual cells, thus giving form and rigidity to immature 



Dry Matter < VNitrogenons- 



The Plant. 89 

and succulent growth. The entrance of many comparatively in- 
soluble compounds into the plant is made possible when they 
assume a hydrated form, that is, when they are combined with 
water. Silicon, for example, which forms comparatively insol- 
uble soil compounds, is supposed to enter the plant as silicic acid, 
which through dehydration or loss of water becomes deposited 
as silica. "Water is the chief constituent in green plants, iis 
amount varying from 80 per cent in grasses to 90 per cent in 
root crops. Its amount decreases at the maturing stage. For 
example, timothy grass, which contains on the average 80 per 
cent of water, has when dead ripe 63 per cent of this constit- 
uent. 

The importance of water in the transformation of carbohy- 
drates will be shown in following paragraphs. It is important 
to observe here that the constituents of water form 55.5 per cent 
of starch and that their proportion is equally prominent in other 
carbohydrates. Water bears similar importance in the structure 
and transformations of all the other plant compounds. 

The carbohydrates form a widely distributed and prominent 
group of compounds in the plant kingdom. They may be classed 
in order of increasing complexity as follows : 
Mono-saccharides. 
Di-saccharides. 
Tri-saccharides. 
Poly-saccharides. 
Mono-saccharides are commonly represented by dextrose or 
glucose, which occurs in most fruits. Artificial dextrose or "glu- 
cose syrup" is prepared commercially by the action of hot, dilute 
sulphuric acid upon starch and subsequent removal of the acid 
by means of lime. This is a hexose or six-carbon sugar, being 
composed of six parts of carbon combined with the equivalent of 
six parts of water. This structure, to which the name carbo- 
hydrate (signifying carbon-water union) owes its origin, may be 
confirmed hj gently heating the sugar in a glass tube. Water 
separates from the compound and collects on the adjacent cold 



90 Agricultural Chemistry. 

surface of the tube, while the remaining blackened or charred 
portion denotes the presence of carbon. Glucose is a product of 
the decomposition of all higher carbohydrates. It is about two- 
thirds as sweet as common sugar. 

Levulose or fructose is a mono-saccharide of the samo general 
composition as dextrose and has many properties in common with 
it. The two sugars are commonly associated in fruits. Levulose 
is abundant in honey where it exceeds the amount of dextrose, 
the two forming about 75 per cent of the product. 

No other hexose-sugars occur free in plants, but galactose is a 
compound of this class. It is formed by hydrolysis or addition 
of water to a group of poly-saccharides. called galactans, which 
occur in plants. 

Di-saccharides are represented in the plant kingdom by two 
sugars. Sucrose, or cane and beet sugar, occurs in many plants, 
notably in the juice of sugar cane (16 to 18 per cent), in the 
sugar beet (10 to 18 per cent) , and in the sap of the sugar maple 
(about 90 per cent of the solids). The sweetness of the sap of 
com and sorghum stalks and of peas and other seeds is due to 
appreciable amounts of sucrose. This sugar differs from the 
mono-saccharides in that it crystallizes readily, and this property 
is taken advantage of in purifying the commercial product. By 
the action of the enzyme invertin, which occurs in yeast, sucrose 
is converted into equal parts of dextrose and levulose. hence the 
designation ' ' di-saccharide. ' ' 

This process of ''inversion" may be accomplished also by boil- 
ing sucrose with dilute acids, the product by both methods being 
known as "invert sugar." The change involves the addition of 
one part of water to each part of cane sugar and this reaction 
characterizes the inter-relations of carbohydrates in general, 
which are largely dependent upon differences in content of the 
water-forming elements. 

Maltose or malt sugar, is a di-saccharide occurring in small 
amounts in seeds. Its amount is considerably increased as a 
result of germination, in which the enzyme known as diastase 
converts starch to dextrines and maltose. Crvstallized maltose 



The Plant 91 

contains one part of water. This makes possible a direct con- 
version to lower sugars, and upon inversion by enzymes or acids, 
one part of this sugar yields two parts of dextrose. 

Tri-saccharides are represented in plants by raffinose. This 
sugar occurs in cotton seed and the germs of wheat, barley and 
other seeds. It sometimes occurs in sugar beets, especially as a 
result of disease or injury, and in quantity sufficient to interfere 
with the refining of the beet sugar. Raffinose inverts to equal 
parts of dextrose, levulose and galactose. 

Poly-saccharides are the most abundant of the carbohydrates. 
Starch, which is one of the simpler members of this group of com- 
pounds, is an unknown multiple of a chemical group containing 
six parts of carbon and the equivalent of five parts of water. It 
may be considered as a multiple of the compound dextrose, in 
which each part of dextrose has lost one part of water. Diastase 
of sprouting seeds and the enzyme ptyalin, which occurs in saliva, 
convert starch to a mixture of simpler, gummy carbohydrates, 
knoAvn as dextrines and then to maltose. 

-^Hot, dilute acids invert starch completely to dextrose and by 
this means, in addition to the action of diastase, the chemist de- 
termines the amount of starch in plants. ' ' This process is also, 
as has been stated, the basis for the commercial production of 
com syrup or glucose syrup. The large amounts of starch in 
cereal grains, as barley and com, and in some root crops, as the 
potato, give them value for the production of alcohol and alco- 
holic liquors. Alcohol is not formed directly from starch, but 
is a product of the fermentation of the sugars to which starch 
may be converted by malt extract. 

The amounts of starch found in some plants and plant products 
are as follows, expressed in per cent of the air dried material : 

Per cent 

Rice grain 79.4 

Barley grain 62 . 

Potato tuber 75 . 5 

Bean, grain 42 . 7 

Pea grain 40 . 5 



Percent 

Wheat flour 66.55 

Corn meal 7 1 . 00 

Corn plant (ears glazed) 15. 40 

Corn stover 0.96 

Oat meal 56.23 



92 



A gricuUural CliemiMry. 



Some of the grains and roots named above are familiar as 
sources of commercial starch. This is true of com and the potato. 
Tapioca is a starch preparation from the root of the cas.sava plant 
and sago starch is taken from the interior of the trunk of the 











B1, 



starch granules from various sources. 

sago palm. A single tree of the latter variety may yield 500 
pounds of sago. 

Individual starch granules are readil}' detected in plant cells 
by means of the microscope and under these conditions, the char- 
acteristic markings of the granules of diiferent plants become of 
value in identifying the source of the sample. 



The Plcmt 93 

Dextrine of commerce is a mixture of compounds varying in 
complexity. Its gummy nature gives it value as an adhesive 
paste. Stick-laljels and postage stamps are coated with dextrine. 
Mixtures of dextrines occur in the grains of cereal plants and 
their amount increases at germination as a result of the decom- 
position of starch. The relative proportions of chemical elements 
in starch and the dextrines are the same, but the latter are ap- 
parently simpler groups of a basal compound (Cg H^o Og), 
ascending in complexity toward the composition of starch. Dex- 
trines are precursors of the simple carbohydrate maltose, which 
occurs in germinated grains. 

Galactans are complex poly-saccharides occurring particularly 
in the seeds of leguminous plants, in some of which they are the 
chief carbohydrates. In the process of hydrolysis, these com- 
pounds combine with water to form the comparatively simple 
hexose known as "galactose." 

Cellulose, the basal constituent of woody fibre, is a poly-sac- 
eharide of great importance for its tenacity and rigidity, which 
give form and resistenee to the walls of mature plant cells. It 
rarely occurs free in the plant, but rather as a constituent of 
compound celluloses, such as the inerustiug, lignified celluloses 
or ligno-eelluloses of cell walls. Cotton and hemp fibres are 
single, elongated plant cells, whose walls are composed of nearly 
pure cellulose. By treating these fibres successively with hot, 
dilute acid, Avith hot, dilute alkali and finally with chlorine gas, 
and washing out the products formed, the purest knoA\Ti cellulose 
has been obtained. It is evident that to resist such treatment 
this compound must be extremely stable. It can be brought into 
solution, however, by certain reagents, and when treated with 
strong sulphuric acid, followed by diluting with water and boil- 
ing, it is broken down and partially converted to dextrose. ' 

This brief discussion of the properties of the various carbo- 
hydrates in connection Avith their conmion products of decompo- 
sition, may serve to indicate a common basis of structure for this 
group of plant compounds. Thus, by the union of two mono- 



D4 Agricultural Chemistry. 

saccharides, we have a di-saccharide. An addition of another 
simple sugar produces a tri-saccharide. Further increments re- 
sult in dextrines of increasing complexity and decreasing solu- 
bility until we have as a product, starch. This is a substance 
insoluble in cold water and decomposes with some difficulty. 

By some internal re-arrangement of the chemical elements in- 
volved in the carbohydrate molecule, we may have cellulose pro- 
duced instead of starch. This is an extremely resistant and 
comparatively permanent compound in which apparently the 
stability of the carbohydrates has reached a maximum. These 
constinictive processes take place only in the plant. We can fol- 
low them in the chemical laboratory only in a reversed order, 
proceeding from the complex to the simple. Our knowledge is 
therefore concerned with the general relations of these com- 
pounds, rather than \\ith the actual changes by which they are 
successively produced in the plant. 

The pectin substances and pentosans should be classed under 
the general head of carbohydrates. 

Pectins are insoluble bodies which occur in the flesh of most 
unripe fruits. Upon boiling with water they yield various poor- 
ly defined compounds of gelatinous nature, sometimes referred 
to as pectoses or pectic acids. It is to these bodies that the ''set- 
ting" of fruit jellies is due. On treatment with weak acids or 
alkalies, they yield simple sugars, thereby disclosing their carbo- 
hydrate nature. Besides dextrose, they yield a class of sugars 
containing five parts of carbon and hence designated as pentoses. 
The mucilaginous substances of flaxseed, quince fniit and parts 
of many other plants, are of pectin nature. 

Pentosans are present in considerable amounts in certain 
gummy exudations of plants, such as cheriy gum, which oozes 
from wounds on trees of the prunus genus, and gum arabic of 
tropical Acacias, a genus of leguminous plants. The pentosans 
of gum arabic yield on hydrolysis a pentose sugar called arab- 
inose. Xylose is a pentose sugar obtained from the so-called 
wood gums, or pentosans which are abundant in straws and some? 



The Plant. ' 95 

grains. The pentosans are intimately associated with the cellu- 
lose of plant tissue. They differ from their corresponding sugars, 
the pentoses, by the equivalent of one part less of water. Upon 
boiling with dilute mineral acids each of these compounds takes 
on one part of water. Araban yields arabinose readily, while 
xylan yields xylose only gradually imder these conditions. This 
behaviour demonstrates the carbohydrate nature of the bodies 
under consideration. The following percentages of pentosans 
have been found in some plant materials: — 

Hays 20 per cent 

Gluten feed 17 " 

Linseed meal 1,3 " 

Brewers' grains .' 24 • ' 

Wheat Bran 24 

From 60 to 90 per cent of these compounds in feeding stuffs 
disappears from the digestive tract of herbivora. This may be 
partly due to bacterial fermentation. Since pentosans, when 
assimilated by the animal, appear to have a value similar to that 
of starch, it is evident that in some cases they may be of con- 
siderable importance as constituents of the carbohydrate material 
of feeding stuffs. 

Fats are uniform in their general composition, consisting of 
one part of glycerine combined with three parts of fatty acid. 
The latter constituent controls the nomenclature of the fats. 
Thus, for example, the fat containing three parts of stearic acid 
is known as "tri-stearin," or more commonly as ''stearin." Fats 
which contain two or three different fatty acids in combination 
^vith the same part of glycerine are called "mixed glycerides." 
Acetic acid, which causes the sour taste in vinegar, is a typical 
example of the fatty acids, the simpler members of this group 
of compounds being volatile liquids of characteristic, pungent 
odor similar to that of the acid cited. The higher members of 
the acetic acid series are solid substances ; and the fats in which 
they occur are also solid, in distinction from liquid fats or oils 



96 Agricultural Chemistry. 

produced by lower fatty acids. These acids rarely occur free, as 
in the case of formic acid, which produces the sting of the nettle 
plant; but they usually occur as constituents of neutral fats. 
Oleic, linoleic and linolenic acids are types of three other series 
of fatty acids which are more abundant in plants than the acetic 
acid series. In distinction from the latter, these acids are char- 
acterized by loose chemical bonds, by virtue of which their fats 
take on oxygen, iodine and other active chemical elements. 
Thus, on prolonged exposure to air, oleiu takes up one part of 
oxygen, linolein takes up two parts and linolenin takes up three 
paiis, by weight. This change is accompanied in proportion to 
its extent by "setting" or hardening of the oils concerned. As 
a result, while olein remains liquid even when exposed to the air 
in thin layers and is characterized as a "non-drj'ing" oil, in- 
creasing proportions of linolein and linolenin produce con- 
secutively the "semi-drying" and "drying" oils. 

The high percentages of the latter oils in linseed oil enhancti 
its value as a vehicle for paints, because, having distributed the 
pigments which it carries, it gradually "sets" and forms a du- 
rable protective coating. If the process of oxidation in such an 
oil is hastened bj' exposing it in thin layers upon inflammable 
material, sufficient heat may be generated to caiise spontaneous 
combustion. Ignorance of this fact has caused destructive fires, 
duo to oil soaked rags and similar material. 

Plant fats consist for the most i)art of mixtures of olein and 
linolein with smaller amounts of stearin, i)almitin and lower 
members of the acetic acid series. The proportions of fats ar<' 
such as to maintain a liquid state at ordinary temperatures and 
produce the oils of the seed of cotton, castor bean, flax and other 
plants. The simple fats differ from carbohydrates by a higher 
content of carbon and hj^drogen and lower oxygen content than 
the latter. This higher content of combustible elements renders 
fats of greater fuel value than the other leading plant compounds, 
because of greater oxygen consumption during combustion. This 



The Platd. 97 

property assumes great importance, as a source of heat or energy, 
when the fats are oxidized in the sprouting seed or in the animal 
.body. 

In some remarkable manner, the plant reverses this process and 
constructs its fats from carbohydrates with elimination of oxy- 
gen. The folio-wing figures show the relative composition of a 
typical carbohydrate and a typical fat. 

Per cent 
Carbon 

Carbohydrate (starch) 39.98 

Fat (stearin) 76.78 

Fats occur in plants chiefly as reserves in the seed. The seeds 
of cereal plants such as corn and oats contain only small amounts 
of fat. Flaxseed, cotton-seed, the castor bean and other seeds 
contain oil in sufficient amount to render its extraction on a com- 
mercial scale both feasible and profitable. The fat content of 
some common seeds is as follows: — 



Per cent 


Per cent 


lydrogen 


Oxygen 


6.71 


53.31 


12.45 


10.77 



Per cent 

Barley 1.8 

Wheat 2 

Corn 5.0 

Oats 5.0 



Per cent 

Cotton 20.0 

Sunflower 21.0 

Flax 33.5 

Castor bean 50 . 



The old fashioned home process of soap-making by boiling 
waste grease with leachings from wood ashes depends upon the 
fact that alkali metals, in this case the potassium or ' ' potash ' ' of 
wood ashes, will displace glycerine from fats. Super-heated 
steam also breaks up fats into glj^cerine and fatty acids, and in 
common with the alkali treatment mentioned above, the process 
is called saponification. The glycerine of connnerce is a by- 
product from this process in the soap industry. Since mineral 
oils cannot be saponified, we have here a means of distinguishing 
them from fats. 

Lecithin is a compound closely related to the fats. In place 
of one part of fatty acid in a normal fat it contains phosphoric 
acid combined with a nitrogen-containing, basic compound known 



98 Agricultural Chemistry. 

as choline. Lecithin is sometimes referred to as a ' ' phosphorized 
fat." It occurs in the seeds of cereals and to a gr.^ater extent 
in the seeds of legumes. 

Waxes have some properties in common with the fats and are 
frequently associated with them in the plant and separated with 
them by methods of extraction. They differ from fats in that 
they contain an alcohol of higher weight in place of glycerine, 
this alcohol being combined ^^^th the fatty acid in equal parts. 
Chinese wax and the carnauba wax obtained from the leaves of 
a South American palm are single compounds, while the waxes 
found in the seeds of the palm, flax, cotton and other plants are 
mixtures. The ''bloom" of leaves and fruits, which serves as 
a protective coating, is compose'd of waxes. These compounds 
can be converted to soaps in the same manner as fats, but they 
yield, of course, other alcohols in place of glycerine. 

Terpenes, essential oils, camphors and resins form another 
group of closely related plant compounds. The terpenes belong 
to a class of chemical compoimds known as hydro-carbons, which 
are composed of the elements carbon and hydrogen only. They 
are partly liquids, such as spirits of turpentine, and partly solids, 
such as rubber and gutta-percha. As in the case of carbohy- 
drates, a classification of these bodies in order of complexity is 
in use which separates them into mono-, di- and poly-terpenes. 
Terpenes are products of pitch yielding trees. Turpentine is a 
terpene of special value in the paint industry as a "thinner" 
or solvent for fats and oils. 

The essential oils to which the characteristic odors of flowei-s 
and flavors of fmits are due are partly hydro-carbons, as in the 
ease of oil of turpentine and oil of lavender. Others, such as oil 
of wintergreen and almond oil, contain some oxygen. Heliotro- 
pin of the heliotrope and the compounds to which the aroma of 
the banana, orange and other fruits is due, are essential oils. The 
pleasing smell of new mown hay is due to the essential oil, cou- 
marin. These compounds are of value in the compounding of 
perfumes, cordials and medicines. They are of special signific- 
ance in foods because of their probable effect on palatability. 



The Plant. ,99 

Camphors are obtained by the distillation of certain tropical 
woods. They differ from terpenes in containing oxygen added 
to the elements of the latter. The two classes of compounds are 
apparently closely related products of the chemical processes of 
the plant. 

Resins occur in pitches and are closely allied in composition to 
the camphors. Like terpenes and camphors they may be distin- 
guished from fats by failure to produce soaps by the usual 
process of saponification. 

Organic acids often occur in plants in considerable amounts 
and are responsible for the sour taste frequently observed. They 
are produced by the fermentation of carbohydrates and rarely 
occur free but usually as acid or neutral salts of potassium or 
calcium. The sourness of lemons is due to critic acid. The acid- 
potassium salt of oxalic acid occure in sorrel and acid-calcium 
oxalate has been found in rhubarb. Malic acid is common in 
fruits, and exists as the acid-potassium salt in rhubarb and the 
acid-calcium salt in the berries of the mountain ash, tobacco 
leaves and other plants. The acid-potassium salt of tartaric 
acid is characteristic of the grape, and potassium and calcium 
salts of this acid are found in the pine-apple, sumac beriy and 
other fruits. It is interesting to note in this connection that 
lactic acid develops in com silage as a product of hydrolysis of 
dextrose and other carbohydrates. These acid compounds play 
an important part in the production of characteristic flavors. 

The proteins are compounds of the greatest importance in the 
plant. They are of complex structure, containing not only car- 
bon, hydrogen and oxygen, but also nitrogen and sulphur. This 
large number of constituents makes possible a variety and com- 
plexity of structure fitting them for the delicate and complicated 
reactions which characterize life processes. Proteins form the 
basis of the life-bearing protoplasm and nucleus of each plant 
cell. Although contained in every cell, they are localized chiefly 
in the seed and furnish nitrogen for the first protein structures 
of the seedling. Individual^ proteins are characterized by a eon- 



100 A gHcuUural Cliemistry. 

tent in fixed proportion of the simpler nitrogenous bodies known 
as amino-acids. Asparagin, which is a derivative of an amino- 
aeid, occurs in freshly sprouted asparagus, peas and beans. It 
is produced from seed proteins by enzyme action and is, in part, 
eventually fitted into the proteins of the seedling. 
Plant proteins may be classified briefly as follows : 

1. Albumins: Soluble in pure cold water; coagulated by 
boiling; occur in seeds only in small amounts. 

2. Globulins: Insoluble in water; soluble in salt solutions; 
separate out on diluting or saturating the solution. Most com- 
mon and abmidant of plant proteins. Occur in largest amount 
in the seeds of leguminous plants. Certain globulins appear to 
be characteristic of the seed in which they are found, as with 
avenalin of the oat, maysine of com, and hordein of barley. 
Edestin, the globulin of the hemp seed, however, occurs in sev- 
eral grains. 

3. Alcohol soluble proteins: (Prolamins). Nearly or whoUy 
insoluble in water; soluble in alcohol of from 70 to 90 per cent 
strength. They have been found only in the seeds of cereal 
plants. 

■4. Glutelins: Not dissolved by water, salt solutions, or al- 
cohol; may be extracted by treating the residue of seeds from 
which the other proteins have been removed, w'ith dilute alkaline 
solutions. Isolated and purified with much difficulty. The only 
well defin(^d glutelins are glutenin of the seed of wheat and orys- 
cnin of the seed of the rice. 

5. Co)ijngated (cohipouncl) proteins: These proteins have 
been modified by combining with other compounds. They in- 
clude nucleo-proteins, in which a large proportion of protein is 
combined with a small amount of nucleic acid. Phosphonis is 
l)resent in these compounds, being contributed by the nucleic 
acid. Conjugated proteins of other types occur in the animal 
kingdom, but tlie exact nature of other preparations than nucleo- 
proteins from plants, assigned to this group of compounds, has 
not been clearly established. Such knowledge as we possess in- 



The Plant 



101 



dicates that only small quantities of nucleo-proteins occur in the 
entire seed and that they are chiefly in the tissues of the embryo, 
in which the nuclei of cells are most abundant. 

The approximate amounts of some plant proteins found in 
seeds are given by Osborne as follows : 



Protein 




Albumins 

Leucosin 

Leucosi n 

Leucosin . . 

Phaselin 

Legumelin 

Lep;umelin 

Legamelin 

Legumelin 

Globulins 

Maysin 

Phaseolin 

Avenalin 

Consrlutin 

Le^umin 

Legumin and Vicilin. 

Legumin and Vicilin . 

Legumin and Vicilin . 

Edestin 

Edestin 

Edestin .'. . 

Edestin 

Alcohol soluble proteins 

Gliadin 

Gliadin 

Hordein 

Zein 

Glutelins 

Gintenin 

Glutenin 

Glatenin , 

Glutenin , 



Wheat grain 

Rye grain 

Barley grain 

Kidney bean grain 

Pea meal ( free from outer 

seed coats) 

Lentil meal (free from 

outer seed coats) 

Horse bean meal (free 

from outer seed coats) . . . 
Vetch grain 

Corn grain 

Kidney bean grain 

Oat grain 

Yellow lupine grain 

Vetch grain 

Pea meal (free from outer 

coatinjs) 

Lentil meal (free from 

outer coatings) 

Horse bean meal (free 

from outer coatings) . . . 

Corn grain 

Wheat grain 

Cotton seed meal (oil free) 
Flax seed (grain ) 

Rve grain 

Wheat grain 

Barley grain 

Corn grain 

Wheat grain 

Corn grain 

Oat grain 

Barley grain 



Per cent in the 
dry material 



0.8 -0.4 
0.43 
0.3 
2.0 

2.0 

1.25 

1.5 
1.5 



0.25 
20.00 

1.5 
26.2 
10.0 

10.0 

13.0 

17.0 

0.14 • 

0.6 -0.7 
15.83 
17.6 



4.00 
4.25 
4.00 
5.00 



4.0 -4.5 
3.5 (assumed) 
11.25 
4.50 



102 Agncultural Chemistry. 

Amino-acids, which have been referred to as constituents of 
proteins, occur free to a limited extent in plants. Their struc- 
ture is that of fatty acids into which amino (NH,) groups have 
been substituted for hydrogen atoms other than those of acid 
radicles. They are compounds of only weakly acid or even of 
basic properties. Amino-valerianic acid is a body of this sort 
which has been separated from white and yellow lupine plants 
of two to three weeks' age. Leucin, which is a substituted amino- 
acetic-acid, occurs in smaller amounts with the amino-valerianic 
acid. In some coniferous seeds the amoimt of arginin, another 
amino acid, exceeds that of the amino acids already mentioned. 
Arginin is a di-amino acid, that is, it contains two such amino 
groups. 

Amides are nitrogenous compounds of another class which 
have been the object of considerable study in their relation to 
the feeding of animals. The proportion of the total nitrogen in 
this form at the time of harvesting the plant is of considerable 
importance because of the probable difference in feeding value 
of various nitrogenous compounds. Amides have the structure 
of organic acids, into which amino groups have been substituted 
for the hydroxyl group of acid radicles. They are, as we might 
therefore expect, neutral, salt-like bodies. They require only the 
addition of one part of water to the molecule to become ammo- 
nium salts, and may be considered as derivatives of ammonia as 
well as of acids. Asparagin is an amide found in man}^ plants, 
as in asparagus, peas and beans, especially just after sprouting. 
Glutamiu, Avhich has been found in squash seedlings and beet 
juice with asparagin, is also an amide. These are properly 
double amino compounds, being amides of amino-acids. They 
offer examples of the possible complexity of structure of organic 
nitrogenuous compounds even in their simpler forms. The ami- 
des and amino-acids which occur at intermediate stages of the 
growth of plants, are derived from the disintegration of the seed 
proteins, or from constructive processes in the leaves and are to 



The Plant 103 

a greater or less extent precursors of protein compounds in the 
new seed. Being readily soluble in water, they form ready 
means for the transportation in the sap of protein forming struc- 
tures, and can be placed at the disposal of the reconstructive 
forces in the plant. 

Amines, or compound ammonias, have only a limited practical 
importance as plant compoimds. They are strongly basic com- 
pounds resulting from the replacement of hydrogen in ammonia 
by hydrocarbon radicles. The rank odor of some plants as the 
fetid goose foot and hawthorn is due to compounds of this sort. 

Alkaloids are basic organic compounds involving substitution 
of more complex organic radicles into the ammonia molecule than 
is the case with the amines. By virtue of their basic structure 
they combine with acids ; the salts so formed offer means of iso- 
lating and purifying these bodies. Some of the more common 
alkaloids are nicotine of tobacco ; morphine of the poppy ; strych- 
nine, brucine and curarine of stryohnos wood ; quinine of cinch- 
ona bark; piperin of pepper; solanin of the potato and night- 
shade ; and cocaine of the leaves of the South American cocoa 
tree. Some are of medicinal value as stimulants (strj^chnine), 
others act as narcotics (nicotine, morphine), and still others are 
virulent poisons (curarine, solanin). Curarine is the active con- 
stituent of curare extract with which some wild tribes poison 
their arrow-tips. 

The ash constituents of the plant, usually relatively small in 
amount, are for the most part absolutely essential to its life 
activities. The follo'W'ing chemical elements are always found in 
plant ash : Calcium, potassium, magnesium, sodium, iron, phos- 
phorus, sulphur, chlorine and silicon. Manganese and aluminum 
are occasionally present ; and zinc, barium and other metals some- 
times occur as accidental constituents. 

The following brief table gives the amount and composition of 
the ash of some typical plants. The subject will be taken up 
more in detail in connection with the relative composition and 
food demands of crops. 



104: 



Agnculiural Chemistry. 
Compoaition of the Ash of Plants. 





Pure 




Ash Constituents. Per cent in 


the pure ash. 




Ash 
per 
































Plant 


cent 












Phos- 
phoric 
Acid 


Sul- 








in 
dry 
plant 


Pot- 
ash 


Soda 


Lime 


Mag- 
nesia 


Iron 
Oxide 


phur 

tri- 

oxide 


Silica 


Chlor- 
ine 


Timothy 






















(liay) 


6.82 


34.69 


1.83 


8.05 


3.24 


0.83 


11.80 


2.85 


32.17 


5.19 


Clover (early 






















bloom) 


0.86 


32.29 


1.97 


34.91 


10.90 


1.08 


9.64 


3.23 


2.69 


3.78 


Wheat 






















(grain).... 


1.96 


31.16 


2.07 


3.25 


12.06 


1.28 


47.22 


0.39 


1.96 


0.32 


Wheat 






















(straw) . . . 


5.37 


13.65 


1.38 


5.76 


2.48 


0.61 


4.81 


2.45 


67.50 


1.68 


Oat ( grain ^ . . 
Oat (straw) . . 


3.12 


17. 90 


1 . 66 


3.60 


7.13 


1.18 


25.64 


1.78 


39.18 


0.94 


7.17 


26.42 


3.29 


6.97 


3.66 


1.16 


4.59 


3.21 


46.69 


4.37 


Potato 






















(tuber) 


3.79 


60.06 


2.96 


2.64 


4.93 


1.10 


16.86 


6.52 


2.04 


3.46 


Sujj;ar beet 






















(root) 


3. S3 


53.13 


8.92 


6.08 


7.86 


1.14 


12.18 


4.20 


2.2S 


4.81 


Corn (grain) . 


1.45 


29. 7S 


1.10 


2.17 


15 52 


0.76 


45.61 


0.78 


2.09 


0.91 


Corn (stalks) 


5.33 


36.30 


1 20 


10.80 


5.70 


2.30 


S.30 


5.30 


28.80 


1.40 



The ash constituents of plants occurring in the seed are present 
there alnio.st entirly as constituents of organic compounds. The 
hulls of the oat and other grains, which are not a part of the 
seed proper, have been found to contain considerable amounts of 
inorganic compounds, among which silica is especially notable. 
The large amount of this ingredient in cereal straws is supposed 
to be in inorganic form, and phosphorus and sulphur have been 
shown to be present in' the stems of legumes and other plants at 
early stages of growth to a large extent as constituents of inor- 
ganic compounds. "When the plant is burned, sulphur, phos- 
phorus and other acid forming elements which are present in 
organic compounds, are converted to acid radicles. These acid 
radicles combine with basic radicles simultaneously formed from 
calcium, potassium and other metallic elements in the plant. 
This results in tlie jinxluction of inorganic salts, such as potas- 



I 



The Plant. 



105 



sium sulphate and calcium phosphate, in the ash. Any excess of 
the basic elements over the acid forming elements will combine 
with the carbonic acid present in the air as a result of the process 
of combustion, and will occur in the ash as carbonates. The large 
amount of potassium carbonate in wood ashes is formed in this 
manner. On the other hand, any excess of acid forming elements 
in the plant will be lost by volatilization and will fail to appear 
in the ash. It is thus evident that the composition of the ash 
gives little clue to the previous status of its constituents in the 
plant. 

In some cases, as with corn grain, where the basic elements of 
the plant are low, a large part of the sulphur and chlorine may 
be lost during incineration. The following data from Fraps il- 
lustrates this point. 

Loss of Plant Elements by Burning. 





Sulphur 


Chlorine 




Total 
per cent 


Per cent 

determined 

from ash 


Total 
per cent 


Per cent 

determined 

from ash 


Corn ( sef^d ) 


0.135 

0.186 

0.196 

0.44 

0.20 

0.188 


Trace 
03 
0.02 
0.07 
0.17 
0.05 


0.04 
0.008 
0.097 
0.032 

0.888 




Peas (pe^d) 


005 


Oats (>eed) 

Cotton seed (meal) 

Tobacco (leaf) 


0.005 
0.008 


Peai litis (fruit) .... 




Timothy (hay) 


864 







In timothy hay and the tobacco leaf, where these losses have 
been slight, the plants contain a high proportion of base forming 
elements. In the other plants tabulated above, a lack of basic 
constituents, together with a high percentage of phosphorus, pre- 
vents complete retention of the other acid forming elements dur- 
ing combustion. With com, Fraps recovered, as an ash con- 
stituent, but one-fiftieth of the total sulphur in that grain. 



106 Agricullural Chemistry. 

Cousiclerable knowledge has accumulated as to the status of 
these ash constituents in the plant. Their functions, however, 
are in many cases not clearlj^ understood. 

Calcium has already been referred to as a constituent of salts 
of organic acids. It occurs widely distributed in this form. Al- 
though essential to the plant and apparently playing an impor- 
tant part in the chemical changes of living cells, its specific func- 
tion is unknown. In some cases it appears to be of advantage in 
forming insoluble salts of organic acids, such as calcium oxalate, 
thus preventing harmful accumulations of free acids in the plant. 
Loew is of the opinion that calcium-protein compounds exist in 
the organized parts of plant cells, from which the nucleus and 
the chlorophyll bodies are built up. He attributes the charac- 
teristic poisonous action of soluble oxalates to their power of de- 
priving tlie.se compounds of their calcium, converting it into the 
insoluble oxalate. According to this view, calcium is partic- 
ularly essential to the metabolic processes in plants. 

Magnesium exceeds calcium in the amount present in seeds 
and, according to Loew, it is attended by phosphoiiis and favors 
the assimilation of the latter body by retaining it in the form of 
soluble compounds. In the same manner, its abundant supply 
in the seed favors easy assimilation of the reserve phosphorus of 
this organ by the seedling. 

Potassium is of common occurrence as a constituent of the salts 
of organic acids. It has also been known for a long time that 
potassium is intimately connected with the formation of starch 
and sugar by plants. It is uniformly abundant in the ash of 
plants rich in these carbohydrates. The lodging of cereal grain 
plants has been attributed to lack of potassium. This theory is 
probably based upon the known stimulating effect of potassium 
on the formation of cellulose and the simpler carbohydrates in 
plant growth, since it has been shown that lodging is due in some 
cases to lack of cellulose compounds in the cell walls of the plant. 
Stoklasa has recently shown that potassium is a constituent of the 
chlorophyll of grasses. This investigator states that it is more 



The Plant 107 

abundant in the chlorophyll structures than in other parts of 
the plant. Loew calls attention to the efficiency of potassium and 
its compounds in condensing certain aldehydes. He attributes 
to this element the function of condensation in the formation of 
carbohydrates and proteins. 

Phosphorus is an essential constituent of the nucleins and nu- 
cleo-proteins around which the activities of the living plant cell 
are centered. This element is also a constituent of the active 
chlorophyll. It is thus seen to be an element with complex and 
most important functions. Phosphorous is also a constituent ol; 
lecithin, the chief function of which has been suggested to be that 
of receiving fatty acids into its molecule and passing them on in 
soluble form to the protoplasm of the seedling. It would thus 
serve as a carrier of fats, which furnish energy for the first 
growth of the plant. 

Sodium has been shown to be dispensable with many kinds of 
plants. There is some evidence that sodium chloride or common 
salt favors the action of diastase and sodium may function in 
this way in the transformations of carbohydrates. A consider- 
able amount of work, especially an extended series of plot ex- 
periments at the Rhode Island Experiment Station with various 
crops, has afforded evidence that sodium favors economical utiliz- 
ation of a low potassium supply, particularly when relatively 
more sodium enters the plant. 

Sulphur is a constituent of all proteins. It forms from 0.4 to 
4.0 per cent of these compounds. It is a constituent of other or- 
ganic compounds known as iso-sulpho-eyanates or mustard oils, 
eonunon to the mustard, turnip and other cruciferous plants. 
The function of these compounds is not known. 

Iron is essential to green plants and lack of it produces a con- 
dition of chlorosis, in which the leaves become bleached. While 
chlorophyll does not contain iron, its action is absolutely depend- 
ent upon this element, small amounts of the latter being extremely 
effective. Iron is a constituent of organic compounds in the 
nuclei of plant cells. 



108 Agricultural Chemistry. 

Chlorine is found to a considerable extent in the ash of the 
mangel and other root crops. It exerts beneficial action in some 
(•ases when applied as a fertilizer in the form of the sodium salt. 
Nobbe found that buck-wheat failed to develop beyond the flower- 
ing stage when lacking a supply of chlorine, and that great ac- 
<-\imulations of starch formed in parts of the stems of the plant 
under investigation. This has led to the view that chlorine, in 
the form of the sodium salt, is essential to the proper activity of 
diastase. 

Silicon is abundant in many plants, such as the gramina*' 
if^rass family, which includes the cereal grains), equisetaceae 
(horse tails) jmd the iron wood, cauto and other trees. Wicko 
found that the ash of the cauto tree contained 96 per cent of sil- 
ica; and the ash of the common scouring rush (Equisetum hye- 
male) has been found to contain 97.5 per cent of this constituent. 
This element accumulates in the external tissues of the plant as 
a constituent of the inorganic compound, silica. Oats, and corn- 
through three generations, have been matured on traces of silicon 
and this element has been considered generalh' as imessential to 
plants. There is considerable evidence, however, that this ele- 
ment favors economical utilization of small supplies of phospho- 
rus by plants. 

Of the occasional constituents of plant ash, manganese has been 
t'oimd to be an essential constituent of laccase, an enzyme in the 
sap of the lac-tree. It is to this enzyme that the setting of lacquer 
varnish is due, and its activity has been found to be proportional 
to the amount of manganese present. The ash of laccase contain'^ 
as high as 2 per cent of manganese. 

Aluminum oecure in some Lycopodiaceae (club mosses) to the 
extent of 22 to 27 per cent of the ash. The recent work of Mose- 
ley on the occurrence of aluminum in certain plants is of great 
interest. He attributes to this element the cause of the disease 
known as ''milk sickness" or "trembles,'' which may break out 
(•ccasionally among dairy cattle and other animals. ^Moseley as- 
serts that animals contract the disease when fed the white snake 



The Plant - 100 

root, which he showed contains aluminum phosphate. By tli*^ 
use of this salt he has reproduced the disease in smaller animals. 
The occurrence of the disease in the southern states has been 
traced to the same salt, but there occurring in the stems of the 
rayless golden rod. In fact, IMoseley believes that wherever 
•'trembles" prevails it is caused by aluminum phosphate, con- 
tained in such plants as the white snalce root or rayless golden 
rod. 

Alpine cress, grown where the soil contained over 20 per cent 
of zinc, was found to contain the following amounts of zinc, ex- 
pressed as zinc oxide and in per cent of the total ash : 

Roots 1 .(56 per cent 

Stem 3.28 " 

Leaf 13.12 " 

Iodine occurs in marine algae to the extent of 0.06 per cent of 
the diy matter. This is of interest as evidence of the assimi- 
lating power of the plant, since sea water contains this element 
to the extent of only one part in four million. 

Bromine also occurs in sea weeds. Copper, lead and other 
metals are sometimes found in plants gro^dng upon soils whicli 
contain such elements. 

Barium has been found in beech and birch trees and in wheat 
grown upon barium-containing soils. The presence of this ele- 
ment as an ash constituent of certain leguminous plants has been 
of considerable practical concern to ranchmen. It has been shown 
to be the active constituent of certain plants producing the loco- 
disease in animals. These ''loco-weeds", as they are commonly 
called, have given trouble in Australia, and losses to stockmen 
from this cause on the United States plains have been heavy. The 
losses in Colorado alone have been estimated at a million dollars 
yearly. Loco-plants grown on some soils are non-poisonous and 
contain no barium. This is a case in which an accidental ash 
constituent has become of marked economic importance. 

From all the evidence at hand, it appears probable that all 
the ash constituents normally present in plants have some func- 



110 A^'icnltural Chemistry. 

tion in the chemical processes of plant growth. In this connec- 
tion the compound phytin is of interest. This is a complex salt 
containing potassium, calcium and magnesium in combination 
with an organic, phosphorus-bearing acid. It has been isolated 
from a number of seeds, including the common cereals, where it 
represents a concentrated form of storage of ash constituents for 
the embryonic plant. Phytin may influence the feeding value of 
these seeds and their products. It contains practically all the 
phosphorus, magnesium and potassium occurring in wheat bran 
and gives to that daiiy feed its laxative properties. 



n 



CHAPTER VI 

FARM MANURE 

For a soil to possess fertility, that is, to be able to properly 
support the growth of plants, certain conditions are necessary. 
The following may be mentioned as being perhaps the most im- 
portant. 

(1) Its mechanical or physical condition must be suitable. 

(2) It must contain sufficient plant food in a form which is 
readily available to the crop. 

(3) It must not contain any appreciable quantity of poisonous 
or injurious substances. 

(4) It must not contain injurious insects, fungi or other or- 
ganisms which are destructive to crops. 

(5) The temperature, sunshine, rainfall and other climatic 
conditions must be suitable. 

Of these the second and third and to some extent the first, are 
matters in which chemistry may be of service. 

Every crop removed from the soil robs it of materials which 
have been used in building up the plant's tissues. Soil which 
annually bears a crop must in time become exhausted of its store 
of plant food and unfitted to bear further crops. Often one con- 
stituent of plant food becomes exhausted first and in many cases 
restoration of this constituent would renew the fertility for some 
time longer. Substances which are added to the soil in order 
to replace the ingredients w^hich have been removed by previous 
crops are called manures. 

All constituents of plants present in a soil, except the carbon, 
are diminished by the growth of crops upon it, but the substances 
which usually first become deficient are combined nitrogen, and 
available phosphorus, calcium, potassium and possibly sulphur. 
Consequently manures are valued according to the quantities 
of these ingredients present in them, although in many cases the 



112 AgricuUural Chemistry. 



other constituents may exert an important influence upon the 
soil. 

Barnyard manure. Of all fertilizers, barnyard manure is the 
oldest and still the most popular. It consists of the liquid and 
solid excreta of the farm stock, plus the litter employed. Early 
Roman writers called atttention to the fact that the application 
of the excreta of farm animals resulted in increased production, 
and from that time to the present the majority of farmers have 
placed their reliance on this class of manures for maintaining 
the fertility of the land. 

A well kept manure heap may safely be taken as one of the 
surest indications of thrift and success in farming. Neglect of 
this resource causes losses which, though little appreciated, are 
vast in extent. "Waste of manure is either so common as to 
breed indifference, or so silent as to escape notice. According 
to recent statistics there are in the United States in round num- 
bers, 19,500,000 horees, mules, etc., 61,000,000 cattle, 47,000,000 
hogs and 51,600,000 sheep. Experiments indicate that if these 
animals were kept in stalls or pens throughout the year and the 
manure carefully saved, the approximate value of the fertilizing 
constituents of the manure produced by each horse or mule an- 
nually would be $27, by each head of cattle $20, by each hog $8, 
and by each sheep $2. The fertilizing" value of the manure pro- 
duced by the different classes of farm animals in the United 
States, would therefore be for horses, mules, etc., $526,500,000; 
cattle $1,220,000,000; hogs, $376,000,000, and sheep, $103,200,- 
000, or a total of $2,225,700,000. These estimates are based on 
the values usually assigned to phosphoric acid, potash and nitro- 
gen in commercial fertilizers, and are possibly somewhat too high 
from a practical standpoint. On the other hand it nm.st be borne 
in mind that no account is taken of the value of manure for im- 
proving the mechanical condition and drainage of soils, which is 
fully as important a consideration as its direct fertilizing value.'' 
It is fair to assume that at least one-third of the value of the 
manure is annually lost through careless methods of manage- 



^ 



Farm Manure. 



113 



iiient. And this estimate is conservative. Even at tliis figure 
we have the tremendous sum of $750,900,000 as an annual loss 
in the United States. This condition is the more unfortunate 
because practically all of it could be prevented. 

In Wisconsin the value of the manure produced annually by 
its 1,300,000 milch cows, 1,100,000 other cattle, 600,000 horses, 
1,000,000 sheep and 1,900,000 swine, based on the above figures, 
is approximately $60,000,000. And it is also true that as large 
a proportion of its valuable constituents is annually lost as in 
any part of the United States. It is safe to say that from the 
farms of "Wisconsin there is an annual loss of at least $20,000,000 
from the indifferent and careless management of the manure 
produced. 

Composition of manure from different animals. The manure 
produced by the various classes of farm animals differs greatly 
in its composition and physical properties. The following table 
gives the average composition of the fresh manure (including 
solid and liquid excrement) of farm animals. It will be seen 
from the table that the differences in composition are largely due 
to the variations in the amount of water present: — 



Average Composition of Fresh Manures. 



Animal 


Water 


Nitrogen 


Phos. Acid 


Potash 


Value 
per ton 


Sheep 


Per cent 
64.0 
70.0 
73.0 
77.0 
75.9 


Per cent 
0.83 
0.58 
0.45 
0.44 
0.45 


Per cent 
0.23 

0.28 
0.19 
0.16 
0.21 


Per cent 
0.67 
0.53 
0.60 
0.40 
0.52 


Dollars 
3.39 


Horse 


2.55 


Pig 

Gow 


2.14 
1.89 


Mixed 


2.08 







A ton of mixed manure of average composition contains ap- 
proximately 5 pounds of phosphoric acid, 10 pounds of nitrogen 
and 10 pounds of potash. 

Manures containing large amounts of water are "cold ma- 



J 14 



Agricultural Chemistry. 



^ 



nures ; ' ' that is, they are manures which heat slowly because the 
high water content checks fermentations. Sheep and horse ma- 
nure are known as ''hot manures," due to a lower water content 
which is favorable to a more rapid fermentation. 

Amount and value of manure from different animals. It is 
sometimes important for the farmer to know the total amount 
and value of the manure produced in a year by the different farm 
animals. In the following table such data are brought together. 
with the amount of manure calculated to the same live weight 
of the various animals. 



Amount and Value of Manure per 1000 lbs. of Live Weight of 
Different Animals. 



Amount per day 



Sheep . 
Calves . 
Hogs . . 
Cows . . 
Horses . 



Pounds 
34.1 
67 8 
5().2 
74.1 
48.8 



Value per day i Value per year 



Cents 
7.2 
6.7 

10.4 
8.0 
7.6 



Dollars 
26.09 
24.45 
37.96 
29.27 
27.74 



If these figures are accepted as representing normal conditions, 
it follows that the sum of thirty dollars may be taken as repre- 
senting the average value of the fresh manure from each 1000 
pounds of live weight. The use of this factor (thirty dollars pei* 
1000 pounds) will enable the student to calculate approximately 
what the nitrogen, phosphoric acid and potash in the manure 
produced on his farm would cost,* if purchased in commercial 
fertilizers, granting of course that the manure is so managed as 
to prevent loss of its valuable constituents. 



*A11 the valuations in the calculations made are based on 15 cents per 
pound for nitrogen and 5 cents per pound for phosphoric acid and for 
potash. This represents in round numbers the market price of these in- 
gredients in commercial fertilizers at the present time. 



Farm Manure. 



115 



Factors which influence the composition of manure. The 

composition of the excrement varies greatly, dependent on the 
following factors: 

(1) The character of the ration. 

(2) Age and kind of animal. 

(3) Kind and amount of absorbents used. 

Considerable variation in the composition of the excreta of 
various animals must necessarily be expected. 

Influence of the ration. The total value of the manure pro- 
duced by a given number of animals is dependent on the quality 
and quantity of the feeding stuffs used in the ration. That the 
different materials used for feeding vary greatly in their fer- 
tilizing value is clearly shown in the following table, which gives 
the quantity of fertilizing materials in one ton of a few of the 
common feeding stuffs and farm products. Additional figures 
are to be found in a table of the appendix: — 

Pounds of Fertilizing Constituents in One Ton. 



Nitrogen 



Phosphoric 
Acid 



Potash 



Value 
per ton 



Wheat straw. 
Corn Silage. . 
Clover hay . . 
Wheat bran . 
Linseed meal 

Oats 

Milk 

Butter 

Pigs (live) . . . 



Lbs. 
11.8 
5.6 
41.4 
53.4 

108.6 

41.2 

10 

2.0 

40.0 



Lbs. 

2.4 

2.2 

7.6 

57.8 

33.2 

16.4 

3.0 

1.0 

17.0 



Lbs. 

10 2 

7.4 

44.0 

32.2 

27.4 

12.4 

3.0 

1.0 

3.0 



Dollars 
2.40 
1.32 

8.79 
12.52 
19.22 
7.62 
1.80 
0.40 
5.00 



The figures represent the fertilizing values of the different 
feeds, provided they are used directly as manures. It is clear 
that the richer the ration is in nitrogen, phosphoric acid and 
potash, the more valuable will be the manure produced by the 
animal. It is necessary now to inquire what proportion of the 
fertilizing content of the food is recovered in the excrement. 



116 Agricultural Chemistry. 

Influence of age and kind of animal. If a mature animal, as 
a steer, for example, is confined in sucli a manner that all the 
excrement, both liquid and solid, can be preserved, it will be 
found that all the nitrogen, phosphoric acid and potash of the 
food will be contained in the excreta. This is when the animal 
is not gaining in weight. None of these constituents will be stored 
in the tissues, but all are voided in the dung and urine. On the 
other hand, only about half of the total dry matter of the ration 
"will be voided in the excrement, a large part of the other half 
having been given off from the lungs as carbon dioxide. While 
the excreta, therefore, contain only about half of the total dry 
matter which was present in the ration, they contain all the con- 
stituents that are generally considered of fertilizing value. 

"With young growing animals, gaining in weight, the above 
statement is incorrect. They retain a certain proportion of the 
nitrogen, potash and phosphoric acid for use in building up their 
bodies. The amount retained depends upon the age of the animal 
and its rate of growth. Experiments indicate that calves retain 
during the first three months of their lives about one-third of the 
fertilizing value of the food consumed, while the other two-thirds 
would be found in the excrement. For the first year of their 
existence they use in growth about one-fifth of the nitrogen, 
phosphoric acid and potash present in the food and as the animal 
ages, the amount gradually diminishes until practically none of 
these materials are retained. "When a mature animal is fatten- 
ing there is practically no drain on the fertilizing value of the 
feed, provided the gain is all fat. This is due to the fact that 
fat contains only carbon, hydrogen and oxygen, and consequently 
its production does not remove any of the fertilizing constituents. 

The above deductions are equally applicable to the other classes 
of farm animals, such as swine, sheep and hoi*ses, and the age of 
the animal has the same eft'ect on the value of the manure. 

Influence of milk production. In the case of the cow another 
factor is introduced, as a certain proportion of the nitrogen, 
phosphoric acid and potash is removed in the milk. One hundred 



Farm Alanure. 117 

pounds of milk contain on an average about 0.53 pound of nitro- 
gen, 0.19 pound of phosphoric acid and 0.17 pound of potash. 
An annual yield of five thousand pounds, therefore, removes in 
the milk fertilizing material amounting in value to $4.90. If the 
milk is sold, this is lost to the farm. Where butter is made and 
sold, practically none is carried away, as all the valuable ingre- 
dients are left in the skimmed milk. The fertilizing value of 
500 pounds of butter amounts to about ten cents. Even when 
the milk is sold, fully 85 per cent of the manurial value of the 
food is recovered. 

Eighty per cent of plant food recovered in manure. Taking 
into account the relation between matured and young stock, milk- 
producing and non-milk-producing animals, as found on the 
average farm, it is conservative to assume that at least 80 per 
cent of all the fertilizing constituents present in the materials 
fed on the farm, is voided by the animals in the solid and liquid 
excreta. This includes the amount removed in the milk, that re- 
tained by the young animals during their growing period, and 
consequently, the fertility removed from the farm by the sale of 
animals grown thereon. The fertilizing value of the excrement 
produced from one ton of feeding material is therefore readilj'- 
ascertained by taking 80 per cent of the fertilizing value therein 
stated. From this it will readily be seen that the composition 
of the feeding stuff really determines the value of the excrement. 
The manure (combined solid and liquid excrement) from one ton 
of wheat straw would be worth $1.92, while that from one ton of 
corn meal, wheat bran, or linseed meal, would be worth $5.24, 
$10.01. and $15.37 respectively. 

Reference to the table will show that in most cases the amount 
of nitrogen is the factor determining the fertilizing value of a 
feeding stuff. This is due to the fact that nitrogen is usually 
present in larger proportion than phosphoric acid or potash, and 
is much more costly when purchased. Wheat bran and linseed 
meal, however, are particularly rich in both phosphoric acid and 
potash. 



118 



Agricultural Chemistry. 



Effect of bedding on value of manure. Bam yard manure, 
as the term is generally used, includes in addition to the excreta, 
the litter or bedding iLsed to absorb the urine. The following 
table gives the composition of some of the materials used for 
bedding : — 

Fertilizing Constituents in One Ton of Litter. 



Nitrogen 


Phosphoric Acid 


Potash 


Wheat straw 

Oat straw 

Clover straw 


Lbs. 
11.8 
12.4 
29.4 
4 
20.0 


Lbs. 
2.4 
4.0 
8.4 
6.0 


Lbs. 
10.2 

24 8 

25 2 


8aw dust 


14 


Peat 





The richer the bedding the more valuable will be the manure. 
The materials commonly used for bedding are low in the elements 
of fertility, so that the use of large amounts decreases the worth 
per ton of the manure, but in any case sufficient litter should be 
used to absorb all the liquid excrement. 

Calculating the amount of manure from the ration. The to- 
tal weight of manure that will be produced from the material 
fed an animal can be calculated with considerable accuracy. Ex- 
periments have shown that about 50 per cent of the dry matter 
present in the ration is recovered in the excrement. The least 
amount of bedding that will absorb all urine excreted must con- 
tain dry matter equal to 25 per cent of the dry matter in the 
feeds used; consequently if just enough bedding is used, the 
manure (excrement plus bedding) contains 75 per cent of the 
dry matter in the ration. Since mixed farm manure contains on 
an average 75 per cent of water, or 25 per cent of dry matter, the 
75 per cent of dry matter mentioned above nuist be multiplied 
by four to find the total manure. This gives a result of 300 per 
cent of the dry matter in the ration for the weight of the manure. 
Tn other words if we multiply the drj^ matter of the ration by 
three, we ^\^ll have a close approximation to the weight of the 



Farm. Manure. 119 

manure produced. This method of calculating holds true only 
when the theoretical quantity of bedding has been used. 

In practice the farmer usually uses all the bedding material 
he has at hand, even if it may exceed that necessary to absorb all 
the urine, and such practice is generally considered advisable for 
the reason that such materials as straw or shavings will decay 
much more readily when mixed with the excrement of animals. 
Where more litter than the theoretical amount is used, the method 
of calculation given must be corrected by adding to the total, the 
weight of the bedding in excess of 25 per cent of the dry matter 
of the ration. 

Value of manure. The great importance of bam yard manure 
as a farm resource is appreciated to its full extent by but few 
farmers. A large proportion of those engaged in agricultural 
pursuits seem to have little realization of the immense loss in- 
curred through the waste of this important product of the farm. 
They begrudge the time and labor required to remove it from 
the bam and feeding lot and it is not uncommon to see the pur- 
chase of commercial fertilizers and the waste of farm manure 
going on at the same time and on the same farm. Bams are 
erected on steep hillsides, or even close to the banks of running 
streams, which practice insures a most effective and wasteful loss 
of the valuable constituents of the manure heap. 

In order to fully emphasize the great value of the manure pro- 
duced on the farm, figures are given for the amount and value 
of the manure produced in one year by a herd of 50 cows giving 
an average individual yield of 15 poimds of milk daily. These 
results are largely taken from Vivian's ''First Principles of Soil 
Fertility." 

It is assumed that the same ration is fed throughout the year. 
In actual practice the ration varies somewhat throughout the 
year, but nevertheless the good feeder aims to keep the composi- 
tion of the ration very much the same even when various sources 
of food materials are drawn upon. 

The following ration will be used as a basis for calculation, 



120 



Agricultural Chemistry. 



vni\\ the daily consumption for a cow weighing 1,000 pounds and 
giving 15 pounds of milk ; 10 pounds of a mixture of one-third 
each of com meal, ground oats and bran; 35 pounds of com 
silage; 15 pounds of clover hay (medium red). This is a good 
practical ration and conforms Avell with the best feeding stand- 
ards. It will be assumed that just the amount of wheat straw 
which would theoretically be necessary to absorb the liquid excre- 
ment is used as bedding. Allowance for milk production is of 
course made by using the factor of 80 per cent as the basis for 
calculating the amounts of fertilizing material recovered in the 
excrement from the total contained in the feeds. 

Fertilizing Constituents of the Manure. 



Nitrogen 1 Phosphoric Acid; 



Potash 



In excrement 
In bedding. . . 
Totals 



Lbs. 
8958.47 

742.01 
9701.08 



Lbs. 
3483.50 

340.22 
3823.72 



Lbs. 
7982.77 

974.28 
8957.05 



The prices paid for fertilizing materials at the present time 
are 15 cents per pound for nitrogen and 5 cents each for phos- 
phoric acid and potash. These prices hold only when raw ma- 
terials are bought, and much higher prices are paid for mixed 
fertilizers. From these prices is calculated the total value of 
the manure produced by 50 cows in one year : 

Value of Manure for Fifty Cows. 

Value of nitrogen $1455 . 18 

Value of phosphoric acid 191 . 19 

Value of potash 447 . 85 

Total value of manure $2094 22 

This means that the fresh manure from 50 cows contains 
amounts of nitrogen, phos]ihoric acid and jiotash that would cost 
the farmer at least $20i)4.22 if purchased in commercial fertil- 



Farm Manure. 121 

izers. The amount of manure produced would weight 811.9 tons, 
giving a value of $2.58 for each ton. How near the actual agri- 
cultural value of the manure will approach the trade value will 
depend upon a number of conditions, such as crop to be fed, 
physical condition of the soil, climate, and especially the manage- 
ment of the manure itself. The same statement applies to com- 
mercial fertilizers, the trade price being no indication of the 
agricultural value of the material, and the farmer who profits 
most from the use of commercial fertilizers is also the one to be 
best repaid for the use of barn yard manure. In experiments 
conducted at the Ohio Experiment Station and covering a period 
of ten years, it was found that the average value of the increase 
of crop produced by one ton of fresh manure amounted to $3.44. 
If 50 cents per ton be allowed, as the cost of applying the manure 
to the field, there still remains a substantial profit, as the result 
of the application. 

How to increase the value of manure. Where a system of 
animal husbandry is practiced, the farmer will find that the most 
economical way to increase the plant food for the farm is by 
purchasing feeding stuffs rich in fertilizing constituents, feeding 
them to the animals and using the manure as a fertilizer. In 
a system of grain farming he wall, of course, be obliged to supplj^ 
his deficiency in plant food by direct purchase of the needed 
elements in the form of commercial fertilizers. The successful 
stockman finds it profitable to reinforce the feeds raised on the 
farm with one or more of the various mill and other by-products 
that are sold as cattle feeds. A farmer who buys large quan- 
tities of concentrates is increasing the fertility of his land pro- 
vided he is taking proper care of the manure. At the University 
Parm there is an annual gain in fertilizer elements from pur- 
chased feeding stuffs over the losses sustained by the sale of ani- 
mals and animal products. 

In purchasing feeding stuffs, one should always consider their 
fertilizing value, as well as their feeding value, for, while the 
substance is bought primarily to feed, it is sometimes possible to 



122 Agricultural Chemistry. 

buy different materials which will serve practically the same as 
feeds and yet varj'- greatly in their value -as fertilizers. It is in- 
deed often sane practice to sell some of the products produced 
on the farm and with the money thus obtained purchase other 
feeding materials. There is scarcely a farm on which such an 
exchange could not be made to advantage. 

The following example will illustrate more clearly what i.s 
meant. At the time of writing it was possible to bu}' uu the 
local market 6.4 tons of clover hay for the price of 5 tons of 
timothy hay, and 5 tons of corn could have been exchanged for 
4.6 tons of wheat bran. Calculating the value of fertilizing 
materials in the manner already described, the results are as. 
follows : 

Fertilizing^; value of 0.4 tons of clover $ 48.55 

Fertilizing value of 4.6 tons of bran 57.32 

Total $105 87 

Fertilizing value of 5 tons of timothy $ 23.00 

Fertilizing value of 5 tons of corn 28 50 

Total $ 51.50 

Gain due to exchange .* 54 . .S7 

B.y a simple exchange of products without any cash outlay the 
fertilizing value of the ration has been increased $54.37 and con- 
sequently the manure produced would have been worth $43.49 
more than that resulting from the use of corn and timothy hay. 
This example is offered merely as a suggestion, which may be 
made of considerable practical value, dependent on the market 
prices of the various feeds. 

In the above example the actual feeding value has been in- 
creased in the exchange due to the increase in protein in both 
clover and bran, with no decrease but rather an actual gain in 
the dry matter purchased. 

Losses in manure. Barn yard manure is a perishable product 
and must be handled with intelligence to obtain its maximum 
vahio. Donbtless as manure is handled on the majority of farms, 



Farm Manure. 



123 



only one-half of its worth is realized. The greatest loss is through 
the waste of the liquid excrement by the use of insufficient bed- 
ding to absorb it. The boring of holes in the floor for the express 
purpose of allowing the urine to run off as rapidly as possible is 
by no means an uncommon practice. The following table gives 
the composition of the solid and liquid excrement : 

Percentage of Fertilizing Constituents in Solid and Liquid Excrements 



Nitrogen 



Solid ; Liquid 



Phosphoric Acid 



Solid 



Liquid 



Soda and Potash 



Solid 



Liquid 



Horses 
Cows . . 
Swine . 
Sheep . 



Per cent 
.50 
.80 
60 
.75 



Per cent 
1.20 
0.80 
0.30 
1.40 



Per cent 
0.35 
0.25 
0.45 
0.60 



Per cent 
Trace 
Trace 

0.12 

0.05 



Per cent 
0.30 
0.10 
0.50 
0.30 



Per cent 
1.50 
1.40 
0.20 
2.00 



Pound for pound the liquid excrement is more valuable than 
the solid, except in the case of swine. It is perfectly safe to say 
that of the total fertilizing material in the manure, two-thirds of 
the nitrogen, four-fifths of the potash, and practically none of 
the phosphoric acid, are found in the urine. It is apparent that 
somewhat over half of the total value of the manure is in the 
urine. Had the liquid portion of the manure been allowed to 
run away, the value of the excrement as calculated in the example 
given above would have been less than $1000 instead of $2049. 

Another fact of great importance in this connection is that the 
plant food in the urine is in a form that is soluble in water and 
consequently more available to plants than that in the solid dung. 
This is particularly true of the nitrogen. The solid excrement 
consists in part of the imdigested portion of the food, and before 
its nitrogen can become available to plants, it must undergo de- 
composition and decay. 

The difference in value of the solid and liquid excrement is 



124 



Agricultural Clieminiry. 



well brought out in the following experiment from the New Jer- 
sey Experiment Station. Two plots were treated with manure, 
the one receiving only solid excrement, while on the other the 
mixed solid and liquid excrement was used. Each plot received 
enough of the manure to supply equal quantities of nitrogen. 
The results are stated in percentage of gain over a check plot 
that received no manure. 



Percentage of Oain in Yield from Manure. 



Solid and liquid 
excrement 




The table clearly shows that the yield from the same amount 
of nitrogen was very much larger from the mixed manure than 
from the solid excrement alone. The experiment also indicates 
that the nitrogen in the liquid excrement was nuich more readily 
utilized by the plant than that in the solid excrement. 

Manure is never so valuable as when fresh ; and the very best 
methods of handling and care, if the manure must be stored, can- 
not prevent some loss of the valuable constituents. For this 
reason, it is advisable when possible, to apply manure to the 
field as fast as it is made. 

Losses in manure from leaching. In addition to the great 
losses due to improper absorption of the urine, the manure suffers 
heavily from leaching by rains. This is probably the greatest 
source of loss. It is often allowed to lie for months in the open 
barn yard, or better, directly under the eaves of the barn, where 
the leaching and washing processes are more complete. Even 
after plenty of litter has been used and all urine absorbed, it is 



Farrn Manure. 



125 



not uncommon to see it placed where it is directly exposed to 
the continuous action of the elements. 

At the New Jersey Experiment Station four samples of ma- 
nure were exposed to the weather for varying lengths of time and 
the losses determined. The results are given in the following 
table : 

Losses in Manure from Leaching. 



Period in days 


Nitrogen 


Phosphoric Acid 


Potash - 


131 

70 


Per cent 
57.0 
44.0 
39.0 
69.0 

51.0 


Per cent 
62.0 
16.0 
63.0 
59.0 

51.1 


Per cent 

72.0 
28.0 


76 


56.0 


50 


72.0 


Average 


61.1 







The average loss amounted to more than 50 per cent of th-^ 
value of the manure during rather short periods. It is very com- 
mon, if not the rule, to find manure exposed on many farms for 
longer periods than here shown. The aggregate loss of the plant 
food of the country by such exposure is appalling. Experiments 
at the Cornell Experiment Station with manure exposed to the 
weather for a period of five months (April to September) gave 
the following data: — 



Horse manure. 
Cow manure . . 



Value at begin- 
ning per ton 



Loss per ton 



P2.S0 
2.29 



$1.74 
0.69 



Loss per cent 



62.0 
30.0 



It is necessary to state that the losses will vary with climatic 
conditions. During heavy rain in warm weather, the losses will 
be heavier than in dry or cold weather. 

Losses from solid excrement by leaching. Not only is the 
liquid portion of the excreta of the animal lost by exposure to^ 



126 



Agricultural Chemistry. 



leaching, but in addition, the solid excrement suffers loss. A 
<?onsiderablc portion of both the phosphoric acid and potash 
eliminated throu<?h the intestine is in a soluble form, and the 




Manure leaching. How the manure in America is wasted. 

chemical changes constantly going on in a manure pile are mak- 
ing soluble the insoluble nitrogenous portions of the dung. 

The following table illustrates the losses -which may occur when 
the solid excrement alone is exposed for varying lengths of time. 



Losses in Solid Excrement from Leaching 




Period in days 


Nitrogen 


Phosphoric Acid 


Potash 


]31 


Per cent 
46.0 
34.0 
25.0 
45.0 

37.6 


Per cent 
72.0 
27.0 
54.0 
42.0 

51.9 


Per cent 

so.o 


70 

76 


10.0 

48.0 


.^10 

Average 


42.0 
47.1 







Farm Manure. 



127 



In addition to the actual losses taking place, the character of 
the material lost is of considerable importance. The nitrogen in 
the portion removed by leaching, is more valuable, pound for 
pound, than that remaining, because it is in a form more im- 
mediately available to the crop. 

In an experiment at the New Jersey Experiment Station two 
plots were treated with quantities of fresh and leached manure, 
both containing exactly the same amounts of nitrogen. The re- 
sults are tabulated below and are stated in percentage of gain 
over a plot receiving no manure. 

Per cent of Gain in Yield from Manure. 



Fresh Manure 



Leached Manure 



First year . . 
Second year 
Third year . 

Average 



.=)2.7 
108.4 
187.5 

116.9 



41.5 
96.8 
89.6 

76.0 



The common practice of open yard feeding, where the manure 
produced during the winter is spread over a considerable area 
and often allowed to remain until late spring, or even into the 
fall, is most wasteful of the fertilizing material it contains. It is 
safe to say that at least one-half of the fertilizing value of the 
manure is lost by such practice. This method of feeding is ex- 
tremely common and in the corn belt of this country it is not 
unusual to see a large feeding yard covered to a considerable 
depth with manure, under ideal conditions for maximum leach- 
ing. 

Losses by fermentation. Manure is very easily decomposed 
and the losses resulting from such decomposition fall entirely on 
the most valuable constituent of the manure, the nitrogen. 
Through the process of fermentation no potash or phosphoric 
acid is lost. These manurial ingredients are wasted only through 
leaching. 



128 Agricultural Chemistry. 

The first evidence of fermentation is the odor of ammonia. 
This is noticeable in the bam, especially if it has been closed 
during the night. It is due to the rapid decomposition of urea, 
the principal nitrogenous body of the urine. Ammonia contains 
nitrogen and when its presence is noticed, it is evident that nitro- 
gen is escaping into the air. It is impossible to entirely prevent 
the formation of ammonia from the urea, but it is possible to 
greatly reduce its loss by providing plenty of absorbing material 
and keeping the manure moist. 

The fermentation of manure is due to different kinds of bac- 
teria. Some of these can exist only in the presence of air and 
are called "aerobic," while others do not require free air and 
are classified as ''anaerobic." The aerobic organisms are re- 
sponsible for the hot fermentation which is the cause of great 
loss of value in manure. It is well known that when manure is 
thrown into loose heaps and contains a large proportion of horse 
or sheep excrement it soon becomes very hot and dry, in fact, hot 
enough to steam, and the temperature may reach 175° Fahr. 
In this condition the common ''fire fanging. " or burning white 
in spots, takes place, and heavy losses of nitrogen are sure to oc- 
cur. Experiments have shown losses of from 30 to 80 per cent 
of the nitrogen. In extreme cases of fire-fanging all the nitrogen 
will be lost. 

If the manure heap is so compact that the air cannot penetrate 
it, the aerobic bacteria are imable to live, and hence hot fermenta- 
tion is prevented. "Where aerobic bacteria are active the soluble 
forms of nitrogen in the manure are partly converted into nit- 
rates and these in turn may be attacked by certain anaerobic 
bacteria called " denitrifiers, " which liberate elemental or free 
nitrogen frojii such compounds. This is an additional reason for 
checking, so far as possible, all aerobic feniientations. The pras- 
ence of large quantities of water in the manure heap holds the 
temperature down, displaces the air and in this way checks 
aerobic fermentations. For this reason, the moist cow and pig 
excrements are not so subject to hot fermentation as that of the 



i 



Farm Manure. 129 

horse or sheep. This explains the sound practice of mixing the 
manure from the various classes of farm animals, when it is 
necessary that it be stored. 

When the manure is in a compact mass and moist the fer- 
mentations that take place are due to anaerobic bacteria. These 
fermentations convert the insoluble plant food in the excrement 
into soluble forms, with little loss of the fertilizing constituents. 
Under the best conditions of care, it is impossible to entirely pre- 
vent losses in stored manure, although if properly preserved it 
may be reduced to about 10 per cent of the nitrogen and none 
of the other two fertilizing constituents. 

Preservation of manure. Saving the urine. From all that 
has been said it must appear perfectly plain that one of the 
greatest losses suffered by the farm is through failure to save the 
liquid excrement of the animal. To insure against such loss, that 
part of the barn floor on which the excrement falls must be so 
tight that none of the liquid can drain away. 

The trough behind the animals should be made absolutely tight 
by the use of pitch, cement, or some other material that is imper- 
vious to water. Besides this precaution, enough litter should be 
used so that all urine is absorbed and none runs away by drip- 
ping, when the manure is removed from the barn. It is often 
of the greatest advantage to finely cut the bedding material. 
This increases its absorbing capacity, and facilitates handling the 
manure. Straw cut in one inch lengths, for example, will absorb 
about three times as much urine as long straw. 

Stockmen who have practiced cutting the bedding assert that 
the great ease with which the manure will be removed and spread 
will repay the cost and trouble, to say nothing of the saving of 
bedding materials. 

Use of preservatives. As has been previously explained, the 
urine of all farm animals contains its nitrogen principally in the 
compound known as urea. This body is rapidly and readily de- 
composed by ferments and changes into amjnonium carbonate. 
This latter substance is volatile and passes off into the air, where 



130 Agricultural Chemistry. 

it can be detected by the sense of smell, that is, by the odor of 
ammonia. The dry manures, as those of the horse and sheep, are 
particularly subject to this loss of nitrogen, which is con- 
tained in the escaping ammonia. Many from the farm have 
suffered with ''smarting eyes" when removing the accumulated 
manure from the horse stable. This is due to the ammonia and 
can be prevented partly by the use of land plaster or gypsum. 
This fixes the ammonia in part, by forming ammonium sulphate, 
which is a non-volatile body. In using gj^psum scatter it on the 
floor immediately after the bam has been cleaned and before the 
fresh bedding has been spread. Prom one-half to one pound per 
animal each day is used in common practice. It is not impossible 
that part of the beneficial results obtained by adding gypsum 
in the manure and to the land comes from the additional supply 
of sulphur. 

Other preservatives, as kainite, muriate of potash and acid 
phosphate, are often recommended as preservatives for manure 
and to prevent the loss of nitrogen. They are reported to be 
injurious to the hoofs of animals and when used should be scat- 
tered on the floor and carefully covered with bedding. There is 
much difference of opinion as to their merits as preservatives, but 
imquestionably they all can effect a partial retention of escaping 
ammonia and thus act as ''barn-sweeteners." They will also 
serve the additional function of reinforcing the manure with fer- 
tilizing materials. They may be used in the same quantity as 
recommended for gypsum. Dry earth has been recommended 
for the same purpose and is especially useful in this regard, par- 
ticularly where it contains a large amount of humus. In some 
parts of the country dry peat or muck soil is in use in the stable 
in connection with the bedding. It should never be used in quan- 
tities sufficient to make the manure dry, as this would result in 
still greater nitrogen losses. 

Haul the manure when fresh. IManure is never so valuable as 
when perfectly fresh, for it i.s impossi])le under the best system of 
management to prevent all loss of its fertilizing ingredients. For 



Farm Manure. 



131 



this reason it is recommended that wherever possible, the manure 
should be hauled directly to the field and spread. It is the most 
economical of time and labor, as it involves handling but once. 
"While it is true that it will be leached by the rain, nevertheless, 
the soluble portion will be carried into the soil, where it is desired 
to have it. When spread in a thin layer, it will not heat, so 
there will be no loss from "hot fermentation;" and where ma- 
nure simply dries out when spread on the ground, there is no loss 
of valuable constituents. 




Wherever possible, haul and spread the manure daily as produced. 



Storing manure. "When it is impossible to remove the manure 
directly to the field, due to weather conditions or lack of avail- 
able fields, the problem of properly storing it will present itself. 
P'rom what has already been said, it is apparent that the two in- 
jurious processes, namely leaching and hot fermentation, must 
be prevented. The effect of leaching may be prevented in two 
ways; either by providing water tight receptacles so that the 
liquid cannot run away, or by keeping the manure under cover 
so as to protect it from the rains. The first method is in general 
use in Europe, where pits or cisterns of cement or other imper- 
vious material are built and in which the manure is stored. Some- 
times a pump is provided, whereby the liquid portion is again 



i;}2 



Agricultural Chemistry. 



l)umped over the more solid portion, keeping it moist and further- 
ing decay with minimum loss. This process makes excellent 
manure but requires time and labor. The more economical way 
for the American farmer to prevent leaching, when manure must 
be stored, is to keep it under cover. A cheap lean-to or shed is 
all that is needed. "Where it is possible, a water-tight floor should 

be provided. 

"Where neither cement cistern nor covered shed is available, 

and it becomes absolutely necessary to store the manure, the heap 







^^ 



When the manure must be stored and there is no cover, build the pile 

as shown above. 

should be made so high and compact that the hardest rain will 
not soak through. The sides should be perpendicular and the 
top dipped toward the center. It is advantageous to have the 
manure saturated with Avater, but large losses of plant food would 
result should the water drain away from the heap. 

Hot fermentation can be controlled by keeping the manure pile 
moist and compact. These two conditions exclude the air from 
the pile and prevent the action of that class of bacteria which 
causes hot fermentation and in addition, require free oxygen for 
their activity. When the heap shows a tendency to dry out. 
water should be added and each daily addition of manure to the 
pile firmly packed into place. This allows decomposition to con- 



Farm Manure. 133 

tinue, liberating the more insoluble plant food from organic con- 
stituents of the manure and greatly improving its mechanical 
condition. Mixing the manure from the various farm animals 
is the very best practice. The drier horse and sheep manure are 
checked in their fermentation by the more moist pig and cow 
excrements. When it becomes necessary to store the manure for 
some time, it is recommended to cover the heap with an inch or 
two of earth. This prevents the escape of any ammonia that may 
be formed. 

Covered sheds save manure. Professor Roberts, formerly of 
Cornell University, was a strong advocate of covered barn yards 
for the conservation of manure. They are simply sheds, with 
good roofs, with or without sides and large enough to allow the 
cattle to freely move about. The bottom is made tight by pud- 
dling clay or using cement. The manure, as removed from the 
barn, is spread about and sufficient bedding distributed over the 
surface to insure cleanliness. The animals trample the accumu- 
lating manure into a compact mass and keep it moist by their 
liquid excrement. This insures an excellent manure, with but 
slight losses of plant food. In addition, it affords exercise and 
a healthful environment for the animals in severe weather. The 
plan has been tried by many dairymen and is generally consid- 
ered very satisfactory. It is said that the cows keep cleaner than 
when stabled and that the milking bam is in a more sanitary con- 
dition. 

The throwing of cattle and horse manure into basement rooms 
to be worked over by the hogs, is from the standpoint of the con- 
servation of plant food, an economical process. By tramping 
and working over the manure, and by adding their own excre- 
ment, the mass is kept moist and fermentation controlled. 

Deep stall manure. In some parts of Europe the ' ' deep stall 
method ' ' of saving manure is in vogue. It consists in excavating 
the stalls where the cattle stand to some depth below the bam 
€oor level. Every day the manure is spread evenly over the stall 
and fresh bedding added. The excrement and bedding are firmly 



134 Agricultural Chemistry. 

packed by the feet of the animal and allowed to remain through- 
out the winter. The manure produced is of excellent quality, 
but for sanitary reasons the practice is hardly commendable, es- 
pecially in the case of dairy cows. 

Composting manure. Where well rotted manure is desired, 
as in market gardening, the practice of composting is in general 
use. This is largely done to avoid the deleterious heating effect 
that would result from applying large quantities of raw manure. 
In addition it is sometimes resorted to in order to destroy noxious 
weed seeds. A favorite method with some market gardeners is 
to compost the manure with earth, peat, or muck. This is done 
by making a foundation of about 6 inches of dirt, and on top of 
this placing alternate layers of manure and soil, moistening the 
mass as the heap grows. The mass is finally covered with a thin 
layer of earth to prevent loss of nitrogen.' After about 2 months 
the pile should be turned over, the materials well mixed and more 
water added, if necessarj^ to keep the compost moist. Sometimes 
sod is used in place of the soil, which gives a fibrous compost very 
desirable for pot and bench work. Refuse materials, such a,s 
kitchen waste, dead animals, etc., can be added with advantage 
to the compost heap, thereby enriching the mass and disposing of 
such materials without the production of offensive odors. Where 
further enrichment is necessary, it is good practice to add bone 
meal or rock phosphate (floats) and one of the potash salts to 
the heap. Tn this way the plant food in the phosphates is made 
more available to plants and the compost more valuable. 

When it is desired to produce well rotted manure in a very 
short time, a small quantity of slaked lime can be mixed with the 
fresh manure. This occasions a rapid decay of the mass, but as 
it also entails a lo.ss of more or less nitrogen, the method is not 
to be recommended for general use. 

Applying manure. A manure can be effective only when its 
constituents are brought into contact with the roots of the crop. 
To obtain this contact to its fullest extent, the manure must be 
thoroughly and evenly distributed throughout the depth of the 



I 



Farm Manure. 135 

soil mainly occupied by the roots. For this reason it appears 
best, when possible, to apply the fertilizers to the surface as a 
top dressing, in order that the soluble plant food as it descends 
may come in contact with the plant roots. The manure to be 
used this way must be fine or well rotted, but even fresh manure 
can be so utilized where cut straw or other fine material has been 
used for bedding. The practice of applying the manure directly 
after ploAnng and thoroughly incorporating it with the soil by 
the use of the harrow or cultivator is a good one. 

Spreading the manure and allowing it to lie on the surface 




A poor way of using good manure. 

should be practiced only on level fields where there is no danger 
from surface washing. It has been claimed that when manure 
is spread broadcast and allowed to lie on the surface, there may 
be serious loss of ammonia into the air, but experiments have 
shown that loss from this cause must be very small. Manure 
made during the winter and hauled directly to the field and 
spread on areas that are fairly level, whether fall plowed or on 
sod to be turned under in the spring, is most economical of labor 
and conserves most efificiently the valuable fertilizing materials. 
It may even be spread on the snow, where it is not too deep, with- 
out serious loss. The loss is certainly less than when thrown in 
the open barn yard. 

Manure should be spread. The very common practice of 
hauling manure to the field, there to be thrown into heaps, has 
several serious objections. In the first place it increases the 
work entailed in spreading, as it must be handled twice. When 



13G Agricultural Chemistry. 

manure is so piled there is danger of injurious fermentations, 
witli consequent losses of nitrogen. In addition, the leaching 
from such piles increases the amount of plant food directly be- 
neath and hence produces a rank growth. It is not uncommon 
to lind the next season 's crop spotted by a more luxuriant growth 
and deeper green color on the areas where the manure heaps have 
been placed. This condition is highly undesirable, as it causes 
the crop to mature at different ages and also endangers loss by 
lodging. A crop with a large plant-food supply will have a 








Uneven grain and grass. This bad condition comes from leaving the 
manure in small piles. It should be spread when hauled. 

longer season of growth than one with a meagre supply. If the 
manure is spread directly from the wagon, the danger of uneven- 
ness of growth is largely avoided and the cost of labor reduced. 
When very coarse manure is used, it is advantageous to supple- 
ment the spreading from the wagon by the use of a drag that 
will break up the larger lumps and thus spread it more uni- 
formly. 

Depth to cover manure. Where the manure is so coarse as to 
interfere with tillage, it will become necessarj'^ to plow it under. 
Judgment must be exercised as to the depth to which it should 
be covered. As a general rule, it should not be so deep as to 
prevent access of air and moisture, which are necessary to insure 



Farm Manure. 137 

fermentation and nitritieation. In clay soils it is possible to 
bury the manure so deeply as to prevent decay, while in open 
sandy soils this danger is not so great. In very compact soils it 
has been recommended that the depth should not exceed 4 inches. 
During very dry seasons much harm may result from plowing 
under large amounts of coarse manure, as there may not be suf- 
ficient moisture in the soil to bring about the decay of the organic 
matter. This undecayed material may result in a physical in- 
jury to the soil. 

Applied to sod. A practice that is highly recommended is to 
apply the manure as it is made to meadow or sod land that is 
to be plowed and planted the following spring. In this way what 
is applied in summer or early fall is partly used by the growing 
crop, thus avoiding losses, and when the sod is plowed under the 
entire plant food can be used by the succeeding crop. Manure 
applied to pasture or meadows during the summer or fall aids 
in conserving the moisture by its action as a mulch, as well as 
supplying plant food and inducing a longer season of growth. 

Fresh and rotted manure. The form in which manure should 
be applied is determined largely by the soil on which it is to be 
used. On heavy soils containing large amounts of clay, more 
benefit will be derived from fresh manures than from those that 
are well rotted. The fresh manure warms these cold soils, makes 
them more porous, and the fermentations that take place during 
decay tend to make the soil more mellow. 

On light or sandy soils, on the other hand, those manures that 
are well rotted will be found most beneficial. Such soils are 
likely to suffer from the drying and heating effect of raw, coarse 
manure, and to have their porosity increased to an undesirable 
extent. While it is doubtful if moderate quantities of fresh ma- 
nure are seriously injurious to these soils, nevertheless, if applied 
in large quantities, it is much safer to have the manure well 
rotted. It will then improve the mechanical condition of the soil 
and increase its water retaining power. 

Fresh manure has a forcing effect and tends to produce stems 



138 AgricuUwol Chemistry. 

and leaves at the expense of fruit and grain. It is therefore 
better for early garden truck, grasses and forage j)lants than for 
cereals or fruits. Corn is usually benefited by liberal applica- 
tions of fresh manure. In fact it may be said that when in doubt 
as to where to apply the manui*e. ' ' use it on corn. " It is claimed 
that fresh manure is injurious to sugar beets and tobacco, pro- 
ducing a large beet of low sugar content and a coarse and un- 
desirable tobacco leaf. It is a well known fact that raw manure 
in large quantities is likely to cause lodging with the small grains, 
such as barley, oats and wheat. In the case of sugar beets, ex- 
periments with fresh manure at the New York State Experiment 
Station have given beets of high sugar content and without rank 
le^f growth, results at variance with those of European experi- 
ments. Climate and soil are probably veiy important factors in 
determining what will be the comparative results with the two 
kinds of manure. 

Instead of using the manure directly on the small grains, it 
is good gractice, where corn is grown, to apply it liberally to that 
crop and plant the field to the smaller grains the following year. 
AVhen this is done the danger from rank gro^A^th is minimized. 

Rate of application. As to the rate at which manure should 
be ai)plied, no fixed rule can be given. It will depend upon the 
character of the soil, the quality of the manure, the nature of 
the crop and the frequency of application. German authorities 
consider 7 to 10 tons light, and 20 tons or more heavy, applica- 
tions. Sir Henry Gilbert considered 14 tons per acre, annually, 
excessive for ■\\'heat and barley. For ordinary farm crops it is 
not customaiy to use more than 8 to 10 tons per acre. As a gen- 
eral principle it may be stated that frequent light dressings pay 
belter than very large ones at long intervals. Too liberal appli- 
cations are wasteful. The amount of manure produced on the 
average farm is so small compared with the land to be fertilized 
that it would be utterly impossible to spread it over all the farm 
yearly. For this reason it is considered good practice to apply 
the manure to one cro[) in a rotation, thus covering only part of 



I 



Farm Manure. 



139 



the farm each year. The following three-year plan of rotation 
will explain the above statement; corn, 1 year; grain, 1 year; 
clover, 1 year; the manure is applied to the clover sod. The fol- 
lowing table brings out clearly the relation of plant food removed 
by such a rotation aij described above, and the quantity returned 
by the application of 10 or 15 tons of farm manure of average 
composition once in 3 years. No account is taken of losses by 
drainage or the gain in nitrogen to the soil of probably 50 pounds 
per acre, by the growth of the clover. 



Corn gr?in 30 bushels . . 

Corn stalks 

Barley grain 40 bushels. 

Barley straw 

Ked clover 2 tons 

Total removed 

Manure 10 tons 

Manure 15 tons 



Wt. crop 

dry 
per acre 



Lbs. 
1500 
1877 
1747 
2080 
3763 



Nitrogen 



Phos- 
phoric- 
Acid 



Lbs. 
28 
15.0 
35.0 
14.0 
98. 

190.0 

100.0 
150.0 



Lbs. 
10.0 

8.0 
H).0 

4.7 
24.9 

63.6 

oOO 
75.0 



Potash 



Lbs. 

6.5 
29.8 

9.8 
25.9 
83.4 

155.4 

100.0 
150.0 



We see from this table that it would require once in 3 years 
the application of about 15 tons of manure of average composi- 
tion to replace the plant food removed by the three crops. 

Relation of manure to maintenance of fertility. At the Rot- 
hamsted Experiment Station, England, experiments to determine 
the relative value of farm yard manure and commercial fertilizers 
have been carried on over a very long period of time. On certain 
plots, crops have been grown continuously with no fertilizer, on 
other plots with barn yard manure at the rate of 14 tons per acre 
annually, and on still others, various combinations of commercial 
fertilizers have been tested. The tests extend over 40 years and 
are given in the following table as averages of five 8-year periods. 



140 Agricultural Chemistry. 

Comparative Effect of Manure and Commercial Fertilizers. 



let 8 years. 

2nd 8 years 

3rd 8 years 

4th 8 years 

5th 8 years 

Average (40 years 



Barley- 


-Bushels 


i 
per acre 






Com- 


No 


Manure 


mercial ' 


JNIanure 


Fer- 






tilizers ' 

i 


24 


44 


48 


18 


52 


51 


14 


49 


45 


14 


52 


42 


11 


44 


41 


16 


48 


4.1 



Wheat-Bushels per acre 



No 
Manure 



Manure 



16 
13 
12 
10 
12 

i;; 



34 
35 
35 
28 
39 

34 



Com- 
mercial 

Fer- 
tilizers 



3(5 
39 
36 
32 
38 

3ti 



It will be seen that there was practically no difference between 
the plots dressed with farm manure and those receiving commer- 
cial fertilizers. In fact the test was hardly fair to the manure, 
as excessive quantities of commercial fertilizers were applied. 
The amount of nitrogen added to the wheat was equal to that 
contained in 800 pounds of nitrate of soda, an excessive amount. 
It is believed by some authorities that had the experiment been 
('onducted in America the result would have been more favorabh- 
to the barn yard manure. This judgment is based on the belief 
that nitrification, due to the influence of climate, would be more 
rapid in this coimtry than in England. 

Lasting effect of manure. Bam yard manure, because of its 
slow-decomposing organic matter, has a lasting effect when ap- 
l)lied to the soil. Where, at Rothamsted, a plot was manured an- 
nually for 20 yeai"s, and then received no manure for the next 
'20 years, this effect is clearly sho\m. The follo^^^ng table illus- 
trates this effect. The figures represent the action of the residual 
manure, as no fertilizer was added during the period covered by 
the table. The crop grown wa.s barley and is expressed in bush- 
els per acre. 



Farm Manure. 



141 



Lasting Effect of Manure. 



Effect residual 
luanure 



First five years 

Second five years 

Third five years 

Fourth fiveyeais 

Average (20 years) 




The table shows that the effect of the manure was perceptible 
in yield for at least 20 years after the last application. In fact 
the value of barn yard manure eannot be estimated on the basis 
of the plant food it contains alone. It has a greater value than 
that because of its improvement on the physical conditions of the 
soil and the increased fermentations which result from its ap- 
plication. It is always a safe fertilizer for the inexperienced 
farmer, as there is little danger of lasting injury from its use, 
while it is possible to use commercial fertilizers in such a way 
as to make the soil poorer after their use than it was before. 

Effect of style of farming on fertility. Prominent authorities 
in agriculture believe that in a system of strictly animal hus- 
bandry, where nothing is sold from the farm except animals or 
animal products, and all the manure properly saved and utilized, 
the fertility of the land may be maintained indefinitely without 
the purchase of commercial fertilizers. It should be remembered 
that a positive balance of plant food could not be maintained in 
this way unless additional feeding materials were purchased and 
fed on the farm. This is due to the 20 per cent loss of fertilizing 
materials contained in the growing animals and milk produced. 
"While there may be large stores of potential plant food in the 
soil which could make up the 20 per cent yearly deficit and main- 
tain average crop production, nevertheless, a permanent agri- 
culture could not be founded on such practice. 

In systems of animal husbandry it is the rule to purchase ad- 



142 



Agricultural Chemistry. 



ditional feeding stuffs. The amount of wheat bran necessary to 
offset the losses on a farm from which live stock and milk are 
sold, is shown in the following table. The calculations are based 
on what a farm of 160 to 200 acres could do. Only potash ana 
phosphoric acid are considered, as the supply of nitrogen for 
plant production can be maintained through the growth of legu- 
minous crops. 

Compensation of Losses on a Farm by Purchase of Wheat Bran. 







Potash 


Ph 


osphoric Acid 


Live stock sold 

Milk sold 


Lbs. 
20, 000 
14(),000 

18,000 1 


Lbs. 

40 

250 

290 

:'.06 




Lbe. 
300 
262 


Total 

Bran Purchased 


562 
630 



The table brings out the fact that 9 tons of wheat bran would 
offset the losses sustained by the sale of farm animals and milk. 
"Where cream is sold instead of milk, the amoimt of wheat bran 
necessary to supply the loss of potash and phosphoric acid in the 
stock sold would be about 5 tons. 

It must be clear to the student from what has already been 
said, that losses in fertility are greater in any system of farming, 
where the crops are sold from the farm than when some form of 
animal husbandry is followed, especially if no commercial fer- 
tilizers are purchased. To illustrate this point more fully, the 
following table adapted from a Minnesota bulletin is given. Four 
farms, each containing 160 acres, were assumed. On the first 
nothing but grain was raised and sold. The second was about 
ef[ually divided between grain and stock farming, and the third 
and fourth were devoted exclusively to stock raising and dairy- 
ing, respectively. In the last two cases a small amount of the 
farm produce was exchanged for mill products, which accounts 



I 



Farm Manure. 



143 



for the slight gain in phosphoric acid, but it was assumed that 
no other concentrates or fertilizers were purchased. The de- 
<iidedly smaller loss of nitrogen on the second farm and the actual 
increase of nitrogen on the stock and dairy farms are due to 
fixation of nitrogen from the growth of clover. The figures rep- 
resent pounds of fertilizing material lost or gained on the farm 
in 1 year. 

Effect of Style of Farvdng on Fertility. 



Kind of farming 


Gain or loss in fertility 


Nitrogen 


Phosphoric Acid 


Potash 


All grain 


Lbs. 
-5600 
-1100 
+1100 
+1200 


Lbs. 
-2500 
-1000 
+ 50 

+ 75 


Lbs. 
-4200 


Mixed 


-lOUO 


Stock . . ... 


— (iO 


Dairy 


- 85 







Green manuring. The lowered crop producing power of a soil 
is in many instances due to the rapid decrease in the amount of 
humus which it contains. Humus is formed in most cases from 
the plants which have previously grown on the field and have 
later become a part of the soil. It may be produced from animal 
or vegetable material added as manure. Virgin soils are rich in 
humus, but continued cropping with no provision for maintaining 
the supply may result in its being decreased from one-third to 
one-half in a period of not more than 15 years. Humus is of im- 
portance because it is a storehouse of plant food, especially nitro- 
gen. Most of the nitrogen of the soil is contained in the more 
or less decomposed organic matter present. 

Plowing under green crops, grown for that pui*pose, is one of 
the oldest means of increasing the humus content of soil. By 
this practice, not only is the soil enriched with carbonaceous mat- 
ter derived from the air, but a considerable amount of nitrates 
which would have been formed by nitrification during the growth 



144 



Agricultural Chemistry. 



of the crop, is assimilated, converted into complex organic com- 
pounds in the plant and restored to the soil. Without the crop 
these nitrates would have been to a large extent lost by drainage. 
The planting of ''catch crops" for this purpose is best done in 
the autumn, since nitrification is then very rapid and loss from 
washing out of nitrates by winter rains is to a great extent pre- 
vented. 

For green manuring, two classes of crops are in common use. 











-M 



E.xperinients showing that "green manuring" with legume plants can 
supply all the nitrogen needed by a succeeding crop' (after Wagner). 

To the first class belong such crops as buckwheat, mustard, rye, 
rape, etc. These kinds of plants are efficient in restoring car- 
bonaceous matter and what nitrogen was available for their 
growth. They have added no essential element of plant growth. 
They should be plowed under before seed is produced or other- 
wise the land would be fouled for the next year. 

To the second class belong the legumes. They have all the ad- 
vantages of the first class, but in addition, increase the amount 
of nitrogen in the soil. Tliose most often recommended are red 
clover, the lupines, cow peas, crimson clover, soy bean and the 



I 



Farm Manure. 145 

ordinary field bean and field pea. Red clover in the one most 
commonly used. They produce good results even when the crop 
is harvested and the stubble plowed under. At the Rothamsted 
Experiment Station it has been estimated that 50 pounds or more 
of nitrogen per acre is added to the soil annually in the roots and 
stubble of clover alone. 

Under certain conditions green manuring may be attended by 
dangers. In a dry season the growth of a crop to plow under 
may decrease the moisture content of the soil to a point that is 
harmful to the succeeding crop. In such a season there may also 
be insufficient moisture in the soil to bring about the decomposi- 
tion of the organic matter which is turned under. When green 
manuring is practiced in a dry season, the land should be rolled 
so as to establish capillarity as far as possible. 

Where systems of stock farming are practiced, it appears to 
be a wasteful method to plow under green crops which may be 
suitable for feed. It would be found more profitable to feed them 
to the animal, carefully save the manure and return it to the 
fields. Green manuring will prove desirable in any system of 
farming where the crops are sold from the farm. On the other 
hand, when the farmer is engaged in stock farming and the crops 
are of value as feeds, then turning them under must be considered 
a wasteful practice. 



CHAPTER VII 
COMMERCIAL FERTILIZERS 

It is neither possible nor necessary for all fanners to engage 
in stock raising or dairying in order to maintain the fertility of 
the land. While it is possible, as has been described, to main- 
tain without the purchase of commercial fertilizei's, a positive 
balance of plant food on the fann in the practice of the above 
systems, it is manifestly impossible to do so in a system of grain 
farming where the crops raised are all sold from the farm. In 
the latter system recourse to commercial fertilizers, supplemented 
by green manuring for the purpose of maintaining the humus 
content of the soil, must be made sooner or later. 

At the present time probably $60,000,000 are spent annually 
in the purchase of fertilizers in the United States, and it is no 
exaggeration to say that fully one-half of this is money thrown 
away. This is not an argument against their use, but simply 
means that they should be purchased with judgment and not 
used at all until actual investigation has sho^^•n them to be 
necessary. 

Plant food not the only factor in crop growth. It should be 
remembered that other factors than plant-food supply enter into 
the production of large crops. Improper physical condition of 
the soil, lack of moisture, deficiency of humus, unsuitable soil 
reaction, unfavorable weather, etc.. all may interfere with the 
normal and vigorous development of the plant and thus cause 
diminished crop returns, even when the plant has within reach 
all the food it needs. These unfavorable conditions may partly 
be ameliorated through means available to man, such as drain- 
ing, irrigating, harrowing, liming, etc. Too frequently fertil- 
izers are made to take the place of tillage when they should be 
used to supplement it. That is, fertilizers are more likely to 
give profitable results when used in conjunction with an excel- 



Commercial Fertilizers. 147 

lent physical condition of the soil, and the man who would ob- 
tain best results without fertilizers is the one most likely to 
realize a profit from their use. "The fact that fertilizers can now 
be easily secured, and the ease of application, have encouraged 
a careless use, rather than a thoughtful expenditure of an equiv- 
alent amount of money or energy in the proper preparation of 
the soil. Of course it does not follow that no returns are secured 
from plant food applied under unfavorable conditions, though 
full returns cannot be secured under such circumstances. Good 
plant food is wasted and the profit possible to be derived is 
largely reduced. ' ' Again, in many instances, the ease with which 
commercial fertilizers can be secured tends to a neglect of the 
home resources and one far too commonly sees the waste of farm 
manure and the purchase of commercial fertilizers practiced on 
the same farm. 

What commercial fertilizers contain. Investigation and ex- 
perience have shown that in most instances increased production 
has resulted from the addition to the soil of but three of the 
essential substances found in plants; namely: nitrogen, phos- 
phoric acid and potash. It has been shown that in normal soils 
there are probably sufficient quantities of all the other elements 
which the plant requires. It was customary, soon after the time 
of Liebig, for agricultural investigators to add all the elements 
essential to plant growth, but practice soon showed that to be 
unnecessary, for the reason stated above. Consequently com- 
mercial fertilizers, as placed on the market today, contain only 
nitrogen, phosphoric acid or potash, or mixtures of these ingre- 
dients and these are the only elements giving the fertilizer com- 
mercial value. 

Commercial fertilizers are made from a few basal materials 
which are articles of commerce. Some of these materials contain 
only one of the essential ingredients of a fertilizer, while others 
contain two, but usually one is in such excess that the material 
is used chiefly to furnish but the one element. 

The "complete fertilizer" consists of two or more of these 



148 



Agricultural Chemistry. 



basal materials mixed together to give the desired per cent of 
nitrogen, phosphoric acid and potash. 

Nitrogenous fertilizers. This group of substances may be 
divided into two classes: H) Inorganic or mineral substances; 



mi'"* 










X-.I'' 




Complete 


Without 


Without 


Without 


FertiUzer 


Phosphoric 
Acid 


Potash ■ 


Nitrog-en 



Effect of fertilizer constituents upon oats grown on clay soil. Note the 
scarcity of foliage where no nitrogen was supplied and the low- 
yield of grain where phosphoric acid was lacking. 

(2) organic substances derived from animal or vegetable mate- 
rials. The inorganic materials most commonly used are sulphate 
of ammonia, nitrate of soda and nitrate of potash. 



Commercial Fertilizers. 149 

Sulphate of ammonia. This material is from the gas works 
and is obtained as a by-product in the manufacture of illumin- 
ating gas. It is the most concentrated nitrogenous material in 
the market and contains from 20 to 23 per cent of nitrogen, 
equivalent to about 25 per cent of ammonia. It is very soluble 
in water, does not readily leach out of the soil, and undergoes 
nitrification very quickly, being converted into nitrates. How- 
ever, some plants may take a part of their nitrogen supply di- 
rectly as ammonium salts, when so applied. The sulphate gives 
good results on soils containing plenty of lime. It should not 
be used on soils deficient in lime, because of its tendency to leave 
the soil acid. 

Nitrate of soda. Tliis fertilizer is known under the name of 
"Chili salt petre" and occurs in deposits of considerable extent 
in Chili. When crude it is called '^ caliche" and contains vary- 
ing amounts of impurities, chiefly common salt. It is freed from 
these impurities by solution and crystalization and when put 
upon the market contains from 95 to 97 per cent of nitrate of 
soda. This final product contains from 15 to 16 per cent of 
nitrogen. Chili supplies over a million tons of nitrate a year 
to be used as a fertilizer. This substance contains its nitrogen 
in the most readily assimilable form, and in the form into which 
most other nitrogenous bodies must be converted before they are 
taken up by the plant. It is not fixed by the soil and unless 
growing crops are at hand to take it up, it will be leached out by 
rains. Consequently it should be applied as a top dressing and 
in not too heavy applications. It is best applied early in the 
spring soon after the plants have started their growth and should 
be mixed with at least double its weight of soil before being ap- 
plied, as otherwise harm to the plants may result. It should not 
be applied to grain crops late in the season. 

Nitrate of potash. This is commonly known as "salt petre" 
and is one of the most concentrated fertilizing materials we have, 
since it contains both nitrogen and potash in available forms. 
It contains about 13 per cent of nitrogen and from 42 to 45 per 



150 Agricultural Chemistry. 

cent of potash. It is generally too expensive to use for manurial 
purposes, as it is used very extensively in various manufacturing 
processes. 

Calcium nitrate. This product is manufactured by passing 
strong electric discharges through air. By this means oxides 
of nitrogen are produced by the union of oxygen and nitrogen. 
These gases are absorbed in water with the production of nitric 
acid. This acid is then led into milk of lime, which results in 
the formation of calcium nitrate. The product is next concen- 
trated until it solidifies as a material containing about 13 per cent 
of nitrogen. At the present time it is almost entirely produced 
in Norway, where cheap water power is available, and in cheap- 
ness compares favorably with nitrate of soda. As a fertilizer 
and as a. source of nitrogen it has given excellent results. 

Calcium cyanamide is a comparatively new nitrogen-contain- 
ing fertilizer and is produced by heating calcium carbide in a 
current of air from which the oxygen has been removed. "When 
used as a manure it has in many cases given as good results as 
the same amount of nitrogen applied as nitrate of soda or am- 
monium sulphate. Because of its injurious effect on germinat- 
ing seeds, it should be incorporated with the soil a week or so 
before any seed is so\\'n. It contains about 20 per cent of nitro- 
gen, and is to-day produced in limited quantities in this country. 

Organic nitrogenous materials. In order to bring out clearly 
the relative value of this class of fertilizing materials they will 
be discussed under the following heads; first, thos;^ materials in 
which the nitrogen becomes readily available in a comparatively 
short time by decomposition in the soil ; second, those materials: 
which undergo fermentation very slowly and the nitrogen of 
which only becoiiics available after a long time. Readily avail- 
able matei-ials include such pi'oduots as dried blood, meat scraps, 
tankage, dried fish or fish scrap, eotton-seod meal and castor 
pomace. 

Dried blood. This material is obtained by drying the blood 
from slaughter houses. Two grades are found on the market. 



Commercial Fertilizers. 151 

Imo^Mi as red and black blood. The red variety has been more 
carefully dried, while the black blood has resulted from a too 
rapid drying. The red blood contains from 13 to 14 per cent 
of nitrogen, while the black variety is less constant in composi- 
tion and contains from 6 to 12 per cent. Dried blood ferments 
very readily in the soil and is one of the most valuable organic 
materials. 

Meat scrap or meat meal. This is a packing house product 
and consists of various parts of animal bodies that have been 
kept separate from the tankage. It is rather variable in com- 
position, containing usually from 10 to 12 per cent of nitrogen, 
with a small amoimt of phosphoric acid — about 3 per cent. It 
is often used for feeding purposes, as well as for fertilizer. 

Tankage. This is a general mixture of the refuse material 
from the slaughter houses. It has usually been steam-cooked in 
order to separate the fat and gelatine, a process which renders it 
more easily fermentable in the soil. From the great variations 
in the nature of the materials entering into its make-up, it must 
of necesssity have a variable composition. It contains from 4 
to 9 per cent of nitrogen and from 3 to 12 per cent of phosphoric 
acid. It is a valuable form of fertilizer as it supplies the crop 
with both nitrogen and phosphoric acid. 

Dried fish and fish scrap. Most of the fish fertilizers are 
made from menhaden, a fish that is caught in large numbera 
along the Atlantic coast. The fish are steamed and pressed to 
extract the oil and the remaining "pomace" is dried and ground. 
This material contains from 8 to 11 per cent of nitrogen and 
3 to 5 per cent of phosphoric acid. Some of the fish fertilizers 
consist of the residue of the canning factories, but these are not 
considered so valuable as those derived from menhaden. This 
material readily imdergoes nitrification and is a quick acting 
fertilizer. 

Cotton-seed meal. This is obtained by removing the hulls 
and oil from the cotton seed. The material is then ground and 
put upon the market. It contains about 7 per cent of nitrogen, 



152 Agricultural Chemistry. 

V/2 per cent of phosphoric acid, and 2 per cent of potash. It 
is too good a food material to be used as a fertilizer, as it is con- 
sidered one of the best concentrated feeds on the market. Its 
value as a feed is becoming more and more recognized and it is 
only a question of time when, like linseed meal, it \^'ill no longer 
be available as a fertilizer. 

Castor pomace is a by-product in the manufacture of castor 
oil. It contains 5.5 per cent of nitrogen, about 2 per cent of 
phosphoric acid and 1 per cent of potash. 

Slowly available materials. Under this head are classed such 
materials as leather meal, hoof and horn meal, and hair and wool 
waste. 

Leather. This is a waste product from various factories and 
is sold as raw leather, steamed leather and roasted leather; it 
contains about 7 per cent of nitrogen and in the soil decays verj'^ 
slowly. "When finely ground it is sometimes used to adulterate 
fertilizing material. 

Hoof and horn meal is a by-product resulting from the mak- 
ing of various articles from hoofs and horns; it is very rich in 
nitrogen, carrying about 14 per cent, but decomposes very slowly 
in the soil. 

Hair. This is another product from slaughter houses, and 
when dry contains from 9 to 14 per cent of nitrogen. It is very 
unavailable and should not be used in its natural condition for 
fertilizing purposes. 

Wool waste is the waste product from the woolen mills and 
contains from 5 to 6 per cent of nitrogen and about 1 per cent 
of potash. It is essentially the wool fibres which have become 
so short by repeated spinning, weaving, etc., that they will no 
longer hold together. It is a low grade fertilizer. 

In many state.s all the above resistant materials are prohibited 
from sale as fertilizers. This appears just, since in their original 
form they decay so very- slowly as to make them of little value 
as food for plants. 



I 



Commercial Fertilizers. 153 

Experiments indicate that if nitrate of soda is rated at 100 
per cent, the availability of the other materials will be as follows : 

Per cent 

Nitrate of soda 100 

Blood and cotton-seed meal 70 

Fish 05 

Bone and tankage 60 

Leather, hair, wool waste, etc 2 — 30 

This suggests that for those crops which begin their growth 
early in the spring, the best results will follow the use of Chili 
salt-petre, as the soil is likely to be poor in nitrates and the 
process of nitrification slow at that time. Other crops, as corn, 
for example, which make their growth after the season is well 
advanced, can use the slower acting fertilizers ; as can those crops 
which occupy the ground permanently. 

In ordinary farming it is seldom profitable to purchase nitro- 
genous fertilizers, for the nitrogen of the soil can be maintained 
by means of farm manures and the proper use of leguminous 
crops in the rotation. In intensive farming, as market garden- 
ing, it will be found necessary to make liberal use of nitrogenous 
fertilizers. 

Phosphatic fertilizers. Materials from which phosphoric acid 
is derived are called phosphates. Commercial sources of the 
phosphoric acid of fertilizers are: (1) phosphate rock; (2) bones 
and bone preparations; (3) basic slag; (4) guano. 

Phosphoric acid is found in these materials in combination 
\vdth lime, iron and alumina. In combination with lime it forms 
three different compounds; (1) insoluble phosphate of lime; (2) 
soluble phosphate of lime; (8) reverted phosphate of lime. 

Insoluble phosphate of lime is known as ''tri-calcium phos- 
phate,'" or "bone phosphate of lime" and is composed of three 
parts of lime in combination with one part of phosphoric acid. 
It is insoluble in water and not readily available to plants. The 
principal materials found on the market containing this form 
of phosphate are : — South Carolina rock, Florida rock, Tennessee 



154 Agricultural Chemistry. 

rock, bonas and tankage. They contain from 25 to 30 per cent 
of phosphoric acid. Ground into a fine powder, the first three 
are sometimes sold under the name of "floats," which on account 
of its fineness of division has given beneficial results, especially 
when mixed with stnl)le manure or applied to soils rich in organic 
matter. 

Soluble phosphate of lime. This substance is known under 
several names, as "one-lime phosphate," "acid-phosphate." "su- 
per-phosphate," "acidulated rock," etc. It is the result of 
treating rock phosphates or bones with sulphuric acid. By this 
process the sulphuric acid combines -s^-ith 2 parts of the lime, 
forming sulphate of lime or gypsum. This leaves a compound 
which contains 1 part of lime and 2 parts of water, in combination 
with the ] part of phosphoric acid which was contained in the 
Iri-calcium phosphate. This substance is soluble in water, read- 
ily diffuses in the soil, and is in the most available form for direct 
use by the plant. A good sample of acid-phosphate contains 
about IG per cent of phosphoric acid. While easily dissolved by 
water, it is not leached out, as several constituents of the soil such 
as humus, lime, iron and aluminum compounds have the power 
of fixing and retaining it for the use of plants. 

Reverted phosphate of lime. In making super-phosphate the 
whole of the insoluble jjhosphate is not acted upon. The tri- 
calcium phosphate Avhich remains after the treatment \nth acid, 
when left in contact with a comparatively large amount of soluble 
phosphate, cause,s a reversion of some of the soluble material to 
what is called "reverted" or "gone back" phosphate. It is also 
known i\s "di-ealcium" phosphate, "citrate-soluble," and "pre- 
cipitated phosphate." In composition, this material falls be- 
tween the tri-calcium and mono-calcium phasphates. It is quite 
insoluble in pure Avater, but can be dissolved by weak acids, and 
by water containing carbonic acid, or by ammonium salts. As 
the soil moisture contains salts in solution, as well as carbon di- 
oxide, this phosphate is readily assimilated by plants and is con- 
sidered an available form. This form of phosphate is considered 



Commercial Fertilizers. 



155 



to he more available to the plant than the insoluble or natural 
phosphate ; hence, the soluble and reverted phosphoric acids taken 
together are Imown as the available phosphoric acid. 

Phosphate rock. This substance has already been mentioned 
under insoluble phosphate of lime. Rock phosphate is designated 
usually by the locality from which it is obtained, as:^South 
Carolina rock, Florida rock, Tennessee rock, etc. It contains 25 
to 30 per cent of phosphoric acid and furnishes the chief source 
of the supply found on our markets. Apatite is a purer mineral 








Florida rock-phosphate mining. 

phosphate and it found in considerable quantities in Canada, 
Norway, Sweden and Spain. ^Mention has already been made of 
the finely ground rock phosphate known as "floats." Recent 
investigations indicate that when this material is added to farm 
manure it has a high fertilizing value ; in fact the increased crop 
production at the Ohio Experiment Station, due to adding ground 
rock phosphate to stall manure was nearly as large as that ob- 
tained from the addition of super-phosphate. It would seem 
from these experiments that the comparatively inexpensive floats 
might, partially at least, replace super-phosphate, if used in con- 



156 Agricultural Chemistry. 

nection with manure or on soils rich in organic matter. The 
reason usually assigned for the necessity of incorporating this 
material with organic matter, is that the latter in its decay, lib- 
erates acids, which attack the phosphate and render it more 
available. 

Bone meal or ground bone is a product of the packing houses, 
glue factories and soap works, the raw material being the bones 
of farm animals. These are either ground directly (raw bones) 
or after having been steamed and dried (steamed bones). This 
latter process removes nearly all the fat, tendons and the nitro- 
genous tissue adhering to the bones. The steamed bone which 
comes from the glue or soap factories, is, as a result of the process 
of steaming, poorer in nitrogen and richer in phosphoric acid than 
the raw bones. Kaw bone contains about 2.5 per cent of nitrogen 
and 25 per cent of phosphonc acid, while the average figures for 
steamed bone are 0.5 per cent and 29 per cent of nitrogen and 
phosphoric acid, respectively. The effect of bone meal on crops 
is largely dependent on its degree of fineness, since it will be de- 
composed more quickly in the soil the finer it is ground. Again, 
the raw bone meal decomposes more slowly, due to the presence 
of fat which retards such processes ; while the steamed bones not 
only allow a much more perfect pulverization, but also a more 
rapid decomposition in the soil, and consequently are considered 
of someM'hat higher availability. Both materials contain the 
phosphoric acid in the form of insoluble phosphate of lime. 

Bone ash is incinerated cattle bones, imported from South 
America ; the nitrogenous constituents of the bones have been 
lost in the process of burning. It consists chiefly of the insol- 
uble phosphate of lime and contains from 30 to 35 per cent of 
phosphoric acid. Bone Mack or animal charcoal is a refuse prod- 
uct from sugar refineries and contains about 33 per cent of phos- 
phoric acid. 

Dissolved bone is made by treating raw bone with sulphuric 
acid. By this process the insoluble phosphate is converted into 
soluble phosphate and the organic nitrogenous material into 



Commercial Fertilizers. 157 

soluble forms. This substance contains from 2 to 3 per cent of 
nitrogen and 15 to 17 per cent of available phosphoric acid. It 
will be seen that in respect to its nitrogen content it differs ma- 
terially from dissolved rock or acid phosphate, which does not 
contain this element. The term ''dissolved bone" is often used 
in speaking of ''dissolved rock," as for example, "dissolved 
South Carolina bone." This use of the term is incorrect, as 
there is no bone in South Carolina rock phosphate. 

Basic slag, also called "Thomas slag," or "odorless phos- 
phate," is a by-product in the manufacture of iron and steel 
from pig iron containing phosphorus. It contains from 15 to 20 
per cent of phosphoric acid in a form differing slightly from the 
phosphates already discussed. In this material there are five 
parts of lime combined with one part of phosphoric acipl. The 
material is insoluble in water, but readily soluble in saline solu- 
tions. From the results of numerous experiments it has been 
found that this material has a high degree of availability, about 
equal to one-half that of a soluble phosphate. Its value as a 
fertilizer partly depends upon its fineness of division. The finer 
it is ground the more quickly it will become available. The fact 
that it contains a high lime content has made it particularly de- 
sirable for acid soils, on which it has given excellent results. 

Guano. Many mixed fertilizers and fertilizing materials are 
incorrectly spoken of as " guano. ' ' The term should be applied to 
the natural product only, which consists of the excrement and 
remains of sea fowls, and which have accumulated in certain re- 
gions along the coast of South America and on some of the is- 
lands in the Carribean sea. There are two kinds, dependent upon 
the conditions under which they were formed. When the forma- 
tion took place in a dry warm region, the excrement dried quick- 
ly and remained practically unchanged. This will contain all 
the nitrogen, phosphoric acid and potash originally in the 
manure. Some of the early guanos contained as high as 20 per 
cent of nitrogen, but those now on the market are of poorer 



158 Agricultural Chemistry. 

quality and contain from 2 to 9 per cent of nitrogen, 9 to 19 
per cent of phosphoric acid and 2 to 4 per cent of potash. Where 
the formation has taken place in a damp climate, then ferment- 
ation occurred, resulting in a loss of nearly all of the organic 
nitrogen. If much rain fell, there was also a loss of nearly all 
of the soluble potash salts and soluble phosphates. This has pro- 
duced a product containing 15 to 30 per cent of phosphoric acid 
in the form of insoluble phosphates of lime, iron and aluminum. 
This material is generallj^ converted into a soluble phosphate by 
treatment with sulphuric acid, before reaching the market. 

Potash fertilizers. This class of materials is generally con- 
sidered of relatively less importance as fertilizers than either 
the nitrogenous or phosphatic fertilizers. This is true because 
potash compounds are usually more abundant in the soil than 
either nitrogen or phosphoric acid, and while most crops remove 
larger quantities of potash than of phosphoric acid, the former 
is more likely to be returned to the soil. It has already been 
stated that potash is most abundant in the stems and leaves of 
plants, and as they are the materials generally returned to the 
land in the form of manure, the drain from the soil of this con- 
stituent is therefore much less than in the case of the nitrogen 
and phosphoric acid. Of course, when the M'hole of the crop is 
removed from the soil the loss of this constituent may be verv' 
great. While these are important facts, it must not be assumed 
that the addition of potash fertilizers is unnecessary. It is a 
very necessary constituent of fertilizers, being absolutely essen- 
tial for those intended for light, sandy soils, and for peaty- 
meadow lands, as well as for certain potash-consuming crops, as 
potatoes, tobacco and roots. They are also of especial value for 
clover, grass, corn and fruits; they should be applied in the 
fall on heavy clay soils and in the early spring on sandy soil. 
The former soils generally do not need applications of potash 
salts as much as sandy soils, being naturally rich in this fer- 
tilizer ingredient. 



Coin me re Uil Fertilizers. 159 

The commercial materials on the market are muriate of potash, 
sulphate of potash, sulphate of potash and magnesia, kainit, to- 
bacco stems and wood ashes. 

Muriate of potash is manufactured by concentration from the 
crude minerals obtained from the Stassfurth mines of Germany. 
These mines of Stassfurth are immense saline deposits, formed 
by evaporation of large inland seas, cut off from the ocean by 
geological changes. These deposits are the main source of all 
commercial potash fertilizers. The muriate contains about 50 
per cent of potash, all of which is combined with chlorine. At 
the present price per ton it supplies potash at a cheaper price 
per pound than any of the other materials. It can be used on 
all soils and all crops except a few, such as tobacco, potatoes and 
sugar beets, which appear to be injured in quality by the chlorine 
present. 

Sulphate of potash. This is another concentrated product of 
the Stassfurth industry. What is known as "high grade sul- 
phate" contains about 50 per cent of potash in the form of 
sulphate. A low grade is also made, which contains from 30 
to 35 per cent of potash. The sulphate of potash is of special 
value for those crops injured by chlorides, as mentioned above. 

Sulphate of potash and magnesia. This is sometimes called 
"double manure salt." It is obtained from the Stassfurth 
mines, and contains 25 to 28 per cent of potash. It is a mixture 
of magnesium sulphate and potassium sulphate. Unless the cost 
per pound of actual potash in this material is less than in other 
forms, it has no special quality to recommend it. 

Kainit. This is the most common product of the Stassfurth 
mines and is a mixture of various salts. It contains from 12 to 
14 per cent of potash, chiefly in the form of sulphate. It also 
contains a considerable quantity of common salt, some chloride 
and sulphate of magnesium, a small quantity of gypsum and a 
small amount of potassium chloride. It is a low grade potash 
salt and while it is cheaper per ton, the actual potash costs more 
in kainit than in the muriate or high grade sulphate. For this 



1 {]() 



Agricultural Chemistry. 



reason it is not desirable to purchase it for making home mix- 
tures. As it contains chlorides it should not be used as a fer- 
tilizing material for tobacco, potatoes, or sugar beets. When 
used it should be carefully applied to the soil so that it will not 
come in contact with the seed, as it may seriously interfere with 
germination. 

Tobacco stems. This is a by-product from tobacco factories. 
It readily undergoes decomposition in the soil, its potash thus be- 




rmiish mines at Stassfurth, Germany. Mining potash for fertilizers. 

coming available. It contains from 2 to 2i/> per cent of nitrogen, 
from 6 to 8 per cent of potash and from 3 to 5 per cent of phos- 
phoric acid. In states where it can be secured at a compara- 
tively low price, it can be used very profitablj^ in making fer- 
tilizer mixtures. 

Wood ashes. For many years they were the sole source of 
potasli for fertilizing purposes, but since the introduction of 
the German potash salts, there is less of this material found on 
the market. They are valuable when unleached, containing in 
this condition from 2 to 8 per cent of potash. They are largely 



Commercial Fertilizers. 161 

composed of carbonates of lime, magnesia and potash, with a 
small quantity of phosphates (i/o per cent). The aslies from 
soft woods contain less potash than those from hard woods. Coal 
ashes have practically no value for fertilizing purposes. Wood 
ashes have a beneficial action on the mechanical condition of 
light soils, mainly because of the large amount of lime they con- 
tain. This binds the soil particles together, thus increasing their 
capillary action and improving their tilth. On clay soils there 
is a tendency for wood ashes to cause "puddling." This is 
avoided by applying an equal quantity of land plaster with the 
ashes. 

All the materials mentioned with the exception of tobacco 
stems are soluble in water, so there is no such marked difference 
in availability as was noted in the case of nitrogenous and phos- 
phatic fertilizers. 

Indirect fertilizers. There are a number of substances which 
are beneficial to the land under some conditions, although they 
add neither humiis nor important quantities of plant food. 
Among such materials are lime, gypsum and common salt. 

Lime. There are very few if any soils, which do not contain 
sufficient lime to supply the plant. The chief value of lime ap- 
plications nuist be as an indirect fertilizer. Its action is three- 
fold: — Mechanical, chemical and biological. Its mechanical ef- 
fect on heavy soils is to make them less adhesive and more friable 
and easier to work when dry. On light porous soils its effect is 
exactly the reverse. It binds the particles together, increases 
the cohesive power and improves capillarity. Chemically, its 
action is important. It acts on insoluble potash compounds, 
liberating potash. It aids in the decomposition of organic mat- 
ter. It corrects acidity by combining with the acids present. 
Its biological action is dependent upon the chemical reactions 
it induces. Its presence is a necessary condition to nitrification, 
a biological process. It combines with the nitric acid formed, 
producing nitrates. By maintaining the soil neutral, or slightly 
alkaline, it creates a proper medium for the growth and develop- 



3 62 Agricvltural Chemistry. 

ment of many forms of micro-organisms, which are so necessary 
to the formation of available plant food. 

Lime for agricultural purposes is put upon the market in 
several different forms: — as caustic lime; as hydrate of lime or 
water-slaked lime; as air slaked lime or carbonate of lime; as 
ground limestone rock and as ground 03'^ster or clam shells. The 
caustic or quick lime is the most concentrated form and the most 
active. It is made up of the two elements, calcium and oxygen. 
"When they unite we have quick lime, or calcium oxide, and this 
material when united with carbon dioxide forms calcium car- 
bonate, the chief constituent of limestone and oyster and clam 
shells. When limestone is burned quick-lime or calcium oxide 
is left behind. One hundred pounds of pure calcium carbonate 
will yield on burning 56 pounds of calcium oxide, and 44 pounds 
of carbon dioxide will be driven off. From the quick lime, the 
slaked lime is obtained by addition of water out of contact with 
the air. Fifty-six pounds of caustic become 76 pounds of slaked 
lime. When contact of air is allowed the 56 pounds of caustic 
become 100 pounds of air slaked lime by again combining with 
the carbon dioxide of the air. Thus it ^vill be seen that in 
purchasing lime it will be more economical to buy the caustic or 
quick lime. However, because of its quick action, care must be 
exercised in its use. Finely ground limestone is coming into 
high favor and where it can be obtained at a sufficiently low cost 
is undoubtedly the safest form to use, especially by the inex- 
perienced. Lime should be applied to the surface and if pos- 
sible thoroughly incorporate with the few upper inches of the 
soil. The clovers and other leguminous plants require more 
lime than do the cereals and are much more sensitive to acidity 
of the soil. A good stand of clover, therefore, is an indication 
that the soil contains sufficient lime. 

Gypsum or land plaster is a sulphate of lime and has given 
excellent results with clover and other leguminous plants. It 
is now generally believed that its beneficial action is due to the 
fact that the plaster sets free the unavailable potash of the soil. 



Cominercial Fertilizers. 1G3 

It is of value to those crops that are benefited by the use of 
potash. For that reason it gives best returns when used on soils 
rich in potential potash, as the clays, with practically no bene- 
ficial results when applied to sandy soils. Its use as a source of 
sulphur must not be overlooked, as it is possible that the bene- 
ficial results obtained in many cases by its application will have 
to be traced back to the additional supply of this element. 

Salt has sometimes been used as a manure. It is certain that 
in special cases it has given beneficial results, but in other in- 
stances injury has resulted. It is well known that salt checks 
fermentations of all kinds so that it probably influences the rate 
of nitrification going on in the soil. It is said that adding salt 
will make the straw of wheat stiffer. but this effect is probably 
due to the fact that salt depresses the plant's growth, making 
the straw shorter and consequently stiffer, due to reduced length. 

Mixed fertilizers. The tendency of the fertilizer trade in this 
country has been toward the manufacture and sale of mixed 
fertilizers. They have been sold in the form kno"\\Ti as complete 
fertilizers, which consist of a mixture of two or more of the 
basal materials heretofore described. Where the basal material 
alone is richer in the essential ingredient than is desired by the 
manufacturer, sufficient gypsum, dry earth, peat or other inert 
matter is added to bring the percentage of these ingredients down 
to the desired point. Mixed fertilizers are indiscriminately 
recommended for general use and all sorts of startling claims are 
made for them by the manufacturers. They are offered as uni- 
versal fertilizers, irrespective of the well kno\^^l fact that soils 
differ widely in their characteristics and that the crops vary in 
their food requirements. So-called special fertilizers, designed 
for special crops and supposed to be adapted to their particular 
needs, are common on the market. Some manufacturers offer a 
corn special, a potato special, a tohacco special, etc. Unfortu- 
nately their chief claim lies in their attractive names. The 
science of plant nutrition has not advanced to that stage where 
one can define what the minimum of essential elements necessarv 



164 



Agricultural Chemistry. 



for the maximum growth of the plant should be. And even if 
we had such information, the makers of fertilizer mixtures en- 
tirely disregard the quantities of plant food already existing in 
the soil to be treated. When the farmer studies the apparent 
needs of his fields and understands the subject of fertilization of 
crops, he will prefer to buy the basal fertilizing materials of defi- 
nite, known composition and make the proportion best adapted 
to his needs, rather than buy mixed fertilizers. 

High and low grade fertilizers. As the basal materials used 
in compounding fertilizing mixtures differ greatly in the amounts 
of plant food they contain, it will be seen that products made by 
mixing these materials will contain very different percentages of 
nitrogen, phosphoric acid and potash. If, for example, dried 
blood, bone meal and muriate of potash were used, the fertilizer 
would have a high content of plant food, while if low grade tank- 
age, w^ood ashes, or kainit were employed, the product would 
hav€ a low percentage. The first example illustrates a high 
grade product, while the second would be considered as low 
grade. 

As the low grade material can be sold at a comparatively low 
price, these materials find a ready market, although the plant 
food in the cheap fertilizer actually costs more per pound. This 
fact is clearly brought out in the following table taken from a 
recent bulletin of the New York Experiment Station. (Geneva). 
Avei^age Cost of One Pound of Plant Food to Consumers. 





Nitrogen 


Phosphoric Acid 


Potash 


Low grade complete 
fertilizer 


Cts. 

20.3 

23.2 

19. (i 
18.5 
13.9 


CIS. 
8.0 
7.0 
(5.0 


Cts. 

(J.S 


Medium grade com- 
plete fertilizer 

High grade complete 
fertilizer 


fi.n 

5.0 


Dried blood. 




Nitrate of soda 






Acid phosphate 


5.1 




Muriate of potash 




4.6 



Coi'nmercial Fertilizers. 165 

It will be seen that the price per pound of plant food is very 
much less in high grade goods than in low grade goods, and 
further, that the essential elements can be purchased separately 
more cheaply than in any mixed fertilizer. 

Home mixing. The above facts emphasize the wisdom of the 
purchase of basal materials and home mixing. The difference in 
cost of complete fertilizers and the basal materials per pound 
of plant food is to be partly attributed to the expense of bagging 
and mixing. This, Voorhees has shown to amount to about $8.50 
per ton. That this practice of home mixing is entirely satisfac- 
tory has been abundantly proven by the Eastern Experiment 
Stations. It allows the uniting of the different elements in the 
proportions which have been found to meet best the requirements 
of the crop and the soil on which the crop is to be raised. By 
buying the basal materials separately it is possible to apply the 
different elements at different times. This point may be of 
great advantage in feeding a crop, especially one needing large 
quantities of nitrogen. 

The conditions and materials necessary to do the mixing are 
a good, tight barn-floor, or a dry, smooth earth-floor, platform 
scales, rake, hoe, shovel and screen. 

Selection of commercial fertilizers. It is impossible to give 
definite directions as to the kinds and quantities of fertilizers 
required for different crops, because soils differ greatly in their 
total content of plant food, and we have no direct and safe meth- 
od hy which the amounts of available plant food can be accur- 
ately determined. By noting carefully the growing crops, we 
may get in a general way, some valuable suggestions as to which 
of the constituents is probably lacking in a soil. For instance, 
when the crop has a deep green color, with well developed leaf 
and stalk and luxuriant growth, it may be assumed that the soil 
is not deficient in nitrogen and potash. A rank and excessive 
growth of leaf and stem, with imperfect bud and flower develop- 
ment indicate excessive nitrogen for the potash and phosphoric 



166 Agricultural Chemistry. 

acid present. "When grain crops tend to mature early, with well 
defined, Avell developed, plump and heavy kernels, there will be 
little doubt that the soil contains a good supply of available 
phosphoric acid. Potash fertilizers are, generally speaking, of 
special benefit in the case of leafy plants like tobacco, cabbage, 
beets, clover and potatoes. While some help may be had from the 
above suggestions, nevertheless definite methods of procedure 
have been proposed by several investigators, and will be dis- 
cussed briefly. 

Ville system. "The system which has perhaps received the 
most attention, doubtless largely because one of the first pre- 
sented, and in a very attractive manner, is the one advocated by 
the celebrated French scientist, George Ville. This system, while 
not to be depended upon absolutely, suggests lines of practice 
which, under proper restrictions, may be of veiy great service. 
In brief, this method assumes that plants may be, so far as their 
fertilization is concerned, divided into three distinct groups. 
One group is specifically benefited by nitrogenous fertilization, 
the second by phosphatic, and the third by potassic. That is. 
in each class or group, one element more than any other rules 
or dominates the growth of that group, and hence each particular 
element should be applied in excess to the class of plants for 
which it is a dominant ingredient. In this system it is asserted 
that nitrogen is the dominant ingredient for wheat, rye, oats, 
barley, meadow grass and beet crops. Phosphoric acid is th(^ 
dominant fertilizer ingredient for turnips, Swedes, Indian corn, 
(maize), sorghum, and sugar cane; and potash is the dominant 
or ruling element for peas, beans, clover, vetches, flax, and pota- 
toes. It must not be understood that this system advocates only 
single elements, for the others are quite as important up to a 
certain point, beyond which they do not exercise a controlling 
influence in the manures for the crops of the three classes. This 
special or dominating element is used in greater proportion than 
the others, and if soils are in a high state of cultivation, or have 



Commercial Fertilizers. 167 

been manured with natural products, as stable manure, they 
may be used singly to force a maximum growth of the crop. 
Thus, a specific fertilization is arranged for the various rotations, 
the crop receiving that which is the most useful. There is no 
doubt that there is a good scientific basis for this system, and that 
it will work well, particularly where there is a reasonable abund- 
ance of all the plant food constituents, and where the mechanical 
and physical qualities of the soil are good, though its best use is 
in 'intensive' systems of practice. It cannot be depended upon 
to give good results where the land is naturally poor, or run 
down, and where the physical character also needs improve- 
ment. ' ' 

Wagner system. "Another system which has been urged, 
notably by the German scientist, Wagner, is based upon the fact 
that the mineral constituents, phosphoric acid and potash, form 
fixed compounds in the soil and are, therefore, not likely to be 
leached out, provided the land is continuously cropped. They 
remain in the soil until used by growing plants, while the nitro- 
gen, on the other hand, since it forms no fixed compounds and 
is perfectly soluble when in a form useful to plants, is liable to 
loss from leaching. Furthermore, the mineral elements are rel- 
atively cheap, while the nitrogen is relatively expensive, and the 
economical use of this expensive element, nitrogen, is dependent 
to a large degree upon the abundance of the mineral elements 
in the soil. It is, therefore, advocated that for all crops and for 
all soils that are in a good state of cultivation, a reasonable excess 
of phosphoric acid and potash shall be applied, sufficient to more 
than satisfy the maximum needs of any crop, and that the nit- 
rogen be applied in active forms, as nitrate or ammonia, and in 
such quantities and at such times as will insure the minimum loss 
of the element and the maximum development of the plant. The 
supply of the mineral elements may be drawn from the cheaper 
materials, as ground bone, tankage, ground phosphates and iron 
phosphates, as their tendency is to improve in character; potash 



IGS AgHcultural Chemistry. 

may come from the crude salts. Nitrogen should be applied as 
nitrate of soda, because in this form it is immediately useful, 
and thus may be applied in fractional amounts, and at such times 
as to best meet the needs of the plant at its different stages of 
growth, with a reasonable certainty of a maximum use by the 
plant. Thus no unknown conditions of availability are involved, 
and when the nitrogen is so applied, the danger of loss by leach- 
ing, which would exist if it were all applied at one time, is ob- 
\ iated . " — ( Voorhees. ) 

System based on the analysis of the plant. ' ' Still another sys- 
tem is based on the food requirements of the plant as shown by 
1he analysis of the plant itself. The amoimt of plant food re- 
moved from each acre of ground is calculated from the analysis 
of the plant and a corresponding ainomit is returned to the soil. 
Different formulas are. therefore, recommended for each crop, 
and in tlieso the nitrogen, phosphoric acid and potash are com- 
bined in tbe same proportions in which they are found in the 
})lant. ExpcMMonce shows that it is necessarj'^ to add amounts of 
these fertilizers to the soil that vdW supply more plant food than 
is removed by tbe crop if the maximum results are desired. This 
system may result in a large yield, but cannot be considered an 
economical method of feeding the plant, as one or more of the 
elements is likely to be applied in excess of the requirements of 
the crop. Tt does not take into consideration, for instance, the 
fact that a plant which contains a large amount of one element 
of plant food may possess unusually great power of procuring 
that element from the soil. The principle underlying this sys- 
tem, of course, is the idea tliat to maintain the fertility of the 
.soil unimpaired an amount of plant food equivalent to that re- 
moved by the crop must be returned to \\\e land. To this extent 
the system is similar to the use of l)arnyard manure, but is not 
so effective." 

Money crop system. ''Another system used in ordinary or 
extensive farming is to apply all tbe fertilizer to tbe money crop 



Commercial Fertilizers. 169 

of the rotation. This method is used especially where only one 
crop in a rotation is sold, the others being fed on the farm. A 
liberal supply of food is used to give the maximum yield which 
the climate and season will permit. The amount of food applied 
is in excess of the requirements of the crop and the residue is 
depended upon to help nourish the succeeding crops, or at least 
the one immediately succeeding the money crop. This system 
has some valuable features and is probably the one most in use 
in this country at the present time. 

"Too frequently fertilizers are used by what certain writers 
have called the ' hit or miss ' system. No special thought is given 
to the requirements of the crop or the composition of the fer- 
tilizer, but if a farmer feels that he can afford it and the agent 
is a glib talker, the sale is made. If the buyer happens to ' hit ' 
the food requirements of his crop a profit is secured and he is 
correspondingly happy, while if he makes a 'miss' he feels as- 
sured that there is no value in commercial fertilizers." — Viv- 
ian.) 

Field experiments necessary. These systems described bavj 
their good features, but they do not take into account the import- 
ant fact that soils differ greatly in the amount and availability of 
the plant food they already contain. In order to determine with 
any degree of certainty what particular constituents are needed 
the farmer must conduct some experiments for himself. Thi.s 
can be done by carefully marking off certain portions of the 
field, of definite size and uniforai soil, and using on them differ- 
ent fertilizing materials. Plots one rod wide and 8 rods long, 
and containing 1/20 of an acre, are of convenient size. The dia- 
gram on page 170, taken from Vivian, shows the arrangement 
and kinds and quantity of materials to be used on each plot. 

Careful notes should be made during the growing period and 
at the end of the growing season and when the crop is hai-vested 
comparison made as to the yields by weight obtained. In this 
way definite information will be secured as to whether the soil 



170 



Agricultural Chemisti-y. 



is lacking in one or two, or all three of the constituents of plant 
food in available form. In carrying out field tests such as these 
it should be borne in mind that the results of one year's work 
arc not perfectly reliable, since prevailing weather conditions, 
as well as other factors, may produce very different results. It 
will be well to continue the work for several years in order to 
eliminate any differences due to differences of season. 



No Fertilizer 




IS lbs. Nitrate of Soda 
15 lbs. Sulphate of Potash 
30 lbs. Acid Phosphate 




30 lbs. Acid Phosphate 
IS lbs. Sulphate of Potash 




No Fertilizer 




IS lbs. Nitrate of Soda 
IS lbs. Sulphate of Potash 




IS lbs. Nitrate of Soda 
30 lbs. Acid Phosphate 




No Fertilizer 



It must also be remembered that the requirements for different 
crops will vary. By carrying the plots through several seasons 
and using the rotation common for that particular farm, the 
special crop needs can also be ascertained. 

Amount of fertilizers to be applied. No definite rules can be 
given as to the quantities of commercial fertilizers to be applied, 
for the amount necessary to produce large crops will vary with 
the character and state of fertility of the soil, the kind of crop 



Commercial Fertilizers. lYl 

to be grown, the time and manner of application and many other 
factors. Five hundred pounds per acre may be considered a 
heavy application for ordinary farm crops ; applications of more 
than that amount will only give economical returns in the case 
of special crops grown under an intensive system of farming. 
Heavy applications at long intervals are not as productive of 
good results as light applications more frequently. It is better 
not to make applications of over 200 pounds per acre of any one 
basal material and to vary the amount from year to year until 
experience has shown that economical returns can be expected by 
heavier applications. Lime may be applied at the rate of 1000 
pounds per acre on light soils and double that amount on heavy 
soils. This application once in 5 or 6 years is usually sufficient. 
Fertilizer laws and guarantees. To protect the farmer against 
the sale of fraudulent and spurious goods, the manufacturers are 
compelled by law in most states, to give the actual amounts of the 
different constituents contained in their products. Usually 
they are compelled by law to state on each bag or parcel 
offered for sale the percentage of nitrogen (or ammonia), 
available phosphoric acid and potash. The enforcement of the 
law and the chemical examination of the fertilizers to determine 
if they agree with the guarantee, rests with the State Experiment 
Station, or in some states with the State Department of Agricul- 
ture. The results secured are published in bulletins available 
to the farmers of the state, and should be consulted freely by 
those buying such materials. These laws have resulted in almost 
complete disappearance of materials compounded with the in- 
tention of defrauding, as well as a great lessening in the number 
of brands offered for sale. Nevertheless, statements often ap- 
pear on the bags, which, to say the least, are confusing and may 
mislead the buyer. Phosphoric acid, 10 per cent, for example, 
is often stated as equivalent to bone phosphate, 22 per cent. To 
the buyer the higher figure is attractive and he is led to believe 
that he will obtain something more than the 10 per cent of phas- 



172 



Agricultural Chemistry. 



phoric acid guaranteed. The following example, taken from the 
label of a fertilizer bag, will explain this point more fully: — 



GENERAL CROP BRAND. 

Ouaranteed Analysis. 

Nitrogen . 82 — 1 . 65 per cent 

Ammonia 1.0 — 2.0 

Available Phosphoric Acid s.o — 10.0 

Equal Bone Phosphate 17.0 —21.0 

Total Phosphoric Acid 10.0 —12.0 

Potash Sulphate 11.0 — LS.O 

Potash 6.0 — 7.0 

Color not guaranteed. 

The buyer is only concerned in the total amount of nitrogen, 
available phosphoric acid and potash that the brand contains, 
and these figures alone should dictate the actual worth of the 
material. 



1 



CITAPTEPt VIII 
CROPS. 

Having considered somewhat in detail the chemical composi- 
tion of plants and the functions of the chemical elements con- 
cerned in their growth, we are in a position to discuss in general 
terms the relative composition and food requirements of crops, 
and the factors influencing their composition and feeding value. 
For the sake of convenience, the common crops Avill be considered 
under the following arbitrary divisions: — 

I. Seed crops — including, , 

a. Cereal grains, such as wheat, corn, rye, barley, oats 

and rice. 

b. Leguminous seeds, such as beans, peas, cowpeas and 

soy beans. 

c. Miscellaneous seeds, such as cotton seed, flaxseed, ca.s- 

tor beans and others. 
II. Hay or fodder crops — including, 

a. Common grasses, such as timothy, red top and Ken- 

tucky blue grass. 

b. Cereal plants, such as corn, oats, barley and other 

crops, cut at an immature stage for soiling pur- 
poses, silage, or hay. 

c. Leguminous crops, such as alfalfa and the various 

clovers (which form true hays), and the pea, cow 
pea, vetch and soy bean (when cut green for soiling 
purposes or for curing as hays). 

III. Root crops — including, 

a. True roots, such as mangels, turnips, beets and carrots. 

b. Tubers, or subterranean stems, such as potatoes. 

IV. Fruit crops — including, 

a. Fruit of perennial plants, such as the apple, pear, 
plum, peach, grape and most berries, as well as the 
orange, lemon, banana and other tropical fruits. 



174 



Agricultural Chemistry. 



b. Fruit of annual plants — ^such as melons, pumpkin, 
squash and tomato. 
Y. Forest growth — including, 

hardwooded and softwooded perennial plants. 
A^I. Miscellaneous crops — including, 

tobacco, and the onion, cabbage, and other truck crops. 

In considering the seed crops we must take into account the 
straw as well as the grain. The former portion of these crops 
is not important in all cases as a feeding material, but it always 
stands responsible for a part of the exhaustion of plant food 
from the soil. For this reason the tops as well as the roots of 
root-crops should be considered. 

The yield of crops, both in the total substance produced and 
in its proportion of plant compounds, varies widely. These fac- 
tors control to a large extent the value of the crops as feeding- 
stuffs, and their demands upon the plant food constituents of 
the soil. A rational comparison of the composition of crops can 
be made only upon the basis of yield of dry matter and of the 
individual nutrient compounds or groups of compounds con- 
tained therein, per acre. The following table gives the total 

Yield in Pounds Per Acre. 



Fresh 


Dry 


Crude 


N. free 


Ether 


Crude 


material 


matter 


protein 


extract 


extract 


fiber 


.35,000 


9,870 


1 , (kSO 


4,305 


350 


2,590 


30,000 


(5, 270 


510 


3, 300 


240 


1,800 


18,000 


5,256 


792 


2,430 


198 


1,458 


11,500 


4,416 


356 


2,323 


138 


1,357 


19,000 


3,591 


589 


2,698 


133 


1,748 


60,000 


5,400 


840 


3,3C0 


120 


540 


32,000 


4,320 


570 


3,136 


32 


288 


18,000 


3,798 


378 


3,114 


18 


104 


1,120 


995 


132 


668 


56 


106 


4,000 


3,672 


160 


1,696 


92 


1,480 


1,200 


1,069 


147 


837 


21 


32 


4,000 


3,432 


140 


1,560 


60 


1,400 


18, 4(iO 


4,800 


1,2(K) 


1,900 


200 


750 


12,340 


1,730 


300 


935 


51 


263 



Aeh 



Alfalfa 

Corn 

Red clover 

Timothy 

Hungarian grass. 

Mangels 

Sugar beets 

Potatoes 

Oats 

Oat straw 

I'arley 

Barlev straw 

( 'ahbage 

Tobacco (leaf) . . 



945 
420 
378 
231 
323 
660 
288 
180 

33 
204 

28 
228 
700 
321 



Crops. 175 

yields and the yields of proximate constituents of such compara- 
ble amounts of crops. 

The differences between weights of fresh material and of dry 
matter in the above table are due almost entirely to water lost 
in the process of complete curing or drying. For example, corn 
in the green state consists of nearly 80 per cent of water, potatoes 
have about the same amount, sugar beets contain about 86 per 
cent, and mangels consist of over 90 per cent of this constituent. 
The several hay crops of the preceding table are rather lower in 
water, containing from 60 to a little over 70 per cent. This 
amount is greatly reduced by the curing process so that the hays 
contain only from 10 to 20 per cent. 

The field cured grain crops carry from 7 to 9 per cent of 
moisture in the straw and about 11 per cent in the seed. The 
high water content of some of these crops, aside from its detri- 
mental effect upon keeping qualities, is sometimes of importance 
with reference to economy of transportation. For example, 
since the root crops retain most of their original water content 
during proper storage, it is evident that a given amount of dry 
food material is handled far less economically in them than in 
grains and hays. It will be observed that the enormous acre- 
yields of these crops, particularly of the mangel, are reduced to 
moderate figures when considered in terms of dry matter. 

The high protein content of the legume hays (clover and al- 
falfa) is in marked contrast to the amount of this group of con- 
stituents in the common hays and the cereal crops. This differ- 
ence will be discussed in detail in the consideration of individual 
crops. Mangels also contain a high percentage of ''crude pro- 
tein;" but it has been shown that more than one-half of the 
nitrogen upon which this figure is based is not in the form of 
protein but is contained in amide compounds. This is probably 
true for other root crops, and greatly diminishes their apparent 
protein value. 

With reference to the production of fat, it should be stated 
that while the grains may yield quite pure fats to the chemist's 



]76 Agricultural Chemistry. 

method of analysis, this will be far from true in the case of hays 
and straws. Considerable amounts of chlorophyll \vill contam- 
inate the "crude fats" determined for the hay crops. The high 
yield of ether extract in alfalfa hay, as in the case of other con- 
stituents of this crop, is incident to a large total yield of dry 
matter obtained from the several successive cuttings per season. 
In this respect, this crop possesses a marked advantage in com- 
parison with the others. 

A large proportion of the ash of cereal straws, some of the 
cereal grains, and the common hays, consists of non-essential 
silica. The legumes and root-crops in general, however, are very 
low in this constituent. The excessive ash content of alfalfa, the 
mangel, the cabbage and other crops is notable ; being composed 
chiefly of such essential constituents as lime, potash, and phos- 
phoric acid, it has a significant bearing upon the well-known ex- 
haustive effects of these crops upon the soil. A Imowledge of the 
amount and composition of the ash of crops gives a basis for the 
selection of animal rations, well-balanced in ash constituents. 

The relative drain of some crops upon the soil is shown by the 
tal)]e in the appendix quoted from Warington. The figures 
foi- sulphur trioxide have been corrected in most cases on 
the basis of determinations made at the "Wisconsin Experiment 
Station. The older determinations of sulphur by analysis of 
the ash have been shown to be low. Other data have been com- 
piled from various sources and added to AVarington's table. 

The food requirements of cereal grains, as shown by a general 
survey of the table, are not widely variant. It will be observed 
that the ash constituents are uniformly much higher in the straw 
than in the grain. Nitrogen, on the other hand, accumulates 
chiefly in the grain, about two-thirds of the total nitrogen re- 
moved being found in this part of the crop. The separate con- 
stituents of the ash show great differences in their relative dis- 
tribution between grain and straw. Thus, while potash, soda, 
lime, chlorine and silica are located chiefly in the straw, the 
greater part of the phosphoric acid occurs Avithout exception in 



Crops. 177 

the rain; sulphur trioxide and magnesia are quite evenly- 
divided between the two parts of the crop. 

Nitrogen and phosphoric acid are probably the plant food con- 
stituents most frequently lacking in soils and in many cases their 
depletion is to be attributed to continuous raising and selling of 
grain crops. It is evident that either the manure from grains 
fed on the farm should be carefully husbanded, or equivalent re- 
turns of plant food to the farm should be made by the purchase 
of feeding stuffs or fertilizers. This subject has been fully dis- 
cussed in the chapter on Manures. It applies with particular 
emphasis to cereal crops, because they are wholly dependent up- 
on stores of available nitrogen in the soil for their supply of this 
element and generally thrive best when supplied with available 
forms of phosphoric acid. 

The conservation of the smaller amounts of plant food in cereal 
straws likewise should not be neglected. The practice of dis- 
posing of these straws by burning is a wasteful one, for by this 
treatment the nitrogen which they contain is entirely lost. 

Food requirements of the common grasses. The common 
hays, represented in our table by meadow hay, are essentially 
straw crops, and their food requirements practically duplicate 
those of the cereal crops. Hays of the legumes show marked 
differences from the true hays. While for example, clover hay 
removes twice as much nitrogen from the land as do the cereal 
crops or meadow hay, it should be borne in mind that, like other 
legumes, this crop obtains almost all its nitrogen from the air 
through the activity of bacteria living in association with its 
roots. As will be demonstrated further on, these crops increase 
rather than diminish the supply of nitrogen in the soil. 

The true legume hays develop extensive root systems and draw 
heavily upon the ash constituents of the soil. This applies in a 
limited degree to phosphoric acid, but more particularly to potash 
and lime, which form one-half the total ash of the bean crop, two- 
thirds of the ash of clover hay, and nearly as large a proportion 
in the ease of alfalfa hay. The legume family of plants is es- 



178 Agricultural Chemistry. 

pecially sensitive to acid conditions of the soil. This is probably 
because such a medium is unfavorable for the activity of 
nitrogen-fixing bacteria. This condition cannot develop in a soil 
properly stocked with lime. 

The leguminous grain crops such as beans or peas are less ex- 
hausting to the minerals of the soil than are the hays of legumes. 
for they develop a less extensive root system. These crops sjiow 
the same general distribution of constituents between the grain 
and straw as do the cereal crops, and, as with the latter crops, 
the greater part of the nitrogen and phosphoric acid is removed 
in the seed. 

Requirements of root crops. The true root crops are pre- 
eminently soil-exhausting crops. Not only do they assimilate 
greater amounts of ash constituents per acre than the other 
crops removed from the soil, with the exception of alfalfa, but 
they remove more nitrogen than the cereals or grasses. In the 
ease of turnips, this amount of nitrogen is seen to be twice that 
removed by cereal grains or meadow hay, and in the case of 
mangels, it is three times as much as these crops contain. It is 
important to realize that the root crops are entirely dependent 
upon the soil for this important element of plant food. Potash 
is uniformly conspicuous for its high proportion in the ash of 
these crops. Its presence is explained by the fact alreadj^ ob- 
served, that this mineral is essential to the production of starch 
and sugar, which are predominant compounds in these crops. 
Since the amounts of phosphoric acid removed by these crops are 
also uniformly high, it is apparent, as demonstrated also by prac- 
tice, that they require especially complete and heavy manuring 
when groMTi under intensive cultivation. 

Requirements of fruit crops. This class of crops is less ex- 
haustive and less dependent upon immediate manuring than the 
crops already discussed; the individual requirements will be 
considered later. 

Requirements of forest growth. Timber growth exceeds most 
of the other crops discussed in the annual production of dry mat- 



II 



Crofs. 



179 



ter, but this increase is obtained at small expense in plant food. 
According to Warington, the production of 3000 pounds of dry 
pine timber requires the consumption of only 21/2 pounds of 
potash and 1 pound of phosphoric acid per acre yearly. Harder 




Note the difference in the extent of the root system of the two plants, 
alfalfa and barley. 

woods require rather more of these constituents. The amount of 
nitrogen in wood is very small, amounting to an average of about 
10 pounds for an annual growth of beech wood. Trees produce 
seed only at mature age and then at the expense of material 
stored in the leaves and wood. 



180 Agricultural Chemistiy. 

The litter which accumulates during the earlier years 
growth will therefore be most effective in increasing the value of 
the surface soil by stores of plant food obtained from the deeper 
soil layers. As a result of this process, the manurial require- 
ments of the forest are low and become much smaller than in 
ordinary cropping. 

Requirements of truck crops. The various truck crops diffei- 
widely in productiveness and feeding habits. Of the more im- 
portant ones, the cabbage assimilates large amounts of ash con- 
stituents, with the exception of silica. The heavy yield desired 
with such crops entails a correspondingly high consumption of 
nitrogen and necessitates heavy manuring with this element, as 
well as liberal manuring with potash and phosphoric acid. The 
high content of sulphur tri-oxide in this crop and in the turnip 
and other members of the ciniciferae, suggests that in some cases 
this element may become the limiting factor in plant growth, and 
that the beneficial effects sometimes observed • from the applica- 
tion of gypsum may be due to the sulphur tri-oxide which it 
supplies. 

The tobacco crop is a comparatively light feeder, but makes 
positive demands for nitrogen, potash and lime. 

Crop residues, which include the leaves of root crops, the 
straws of grain crops, the stallcs of tobacco and waste parts from 
trimming, contain sufficient plant food to justify the exercise of 
care to return them to the soil. Potash and lime are the con- 
stituents of most concern in the straws and they are of even 
greater consequence in the leaves of root crops. The common 
practice of spreading tobacco stallis to decay upon the land, 
makes possible, as indicated by the table, the returning of con- 
siderable amounts of potash and also of nitrogen to the soil. 
These crop residues are frequently reduced to ashes to economize 
labor in their disposal, but this practice should be discouraged, 
since it involves a loss of much nitrogen. 

"Whenever the soil will profit l>y the addition of organic mat- 
ter, these materials should be turned in whole. Another prac- 



Crops. 181 

tice, mucli better than burning, is to compost such material witli 
soil. In this way, both nitrogen and the ash constituents are 
conserved as the organic matter decays. 

Individual characteristics of crops may be taken up now more 
in detail. 

Wheat. This important grain represented 25 per cent of the 
value of cereal crops and 13 per cent of all crops in 1900. Sixty- 
two per cent of the cereal products milled in that year were from 
wheat. Over one-third of the farms in the United States raised 
wheat, with a total production in 1900 of 35 billion bushels. 
Extensive breeding of this grain has led to the production of 
about 245 leading varieties. 

The crop is commonly sown in the fall and grown as "winter 
wheat." As a result, it has a longer period of growth and a 
more extensive root system than most of the cereals. The roots, 
which are especially developed in Durum wheat, have been found 
to reach a length of four, and even of six feet. These conditions 
enable the plant to feed effectively upon the soil. The necessary 
omission of spring tillage in the case of this crop, prevents the 
aid of this important stimulus to nitrification and renders wheat 
dependent largely upon manurial supplies of available nitrogen. 
Its extensive root system and long period of growth aid this plant 
in deriving its mineral constituents from the soil and make it 
more independent of available potash or phosphate fertilization ; - 
nitrates or ammonium salts consequently are recommended as the 
chief fertilizer treatment. 

The wheat kernel, according to Bessey, is separated mechan- 
ically into the following proportion of parts : — 

Coatings (or bran layers) 5 per cent 

Gluten layer 3—4 

Starch cells 84—86 

Germ 6 " 

Protein and fat are highest in the germ and bran, ash is high- 
est in the bran, and the fibre is confined almost exclusively to 
this coating. Starch is the characteristic, and by far the most 



182 Agricultural Chemistry. 

abundant constituent in wheat, as it is in all the cereal grains. 
This constituent is highest in the flour, which represents the in- 
terior of the kernel. ( The composition of grains and other crops 
and of their more important products mil be found in tables in 
the Appendix.) 

It is a significant fact that about 80 per cent of the phosphoric 
acid of this grain is located in the bran. This makes possible 
the return of much of this important constituent to the farm in 
wheat bran and its eventual recovery in the manure. The gluten 
or gum-forming portion of the wheat grain is composed of two 
proteins, glutenin and gliadin, which form about 85 per cent of 
the total proteins of the seed. The tenacity of bread dough and 
of macaroni made from wheat flour, is due to gliadin. Consid- 
erable attention has been given to the factors affecting the 
amount and composition of gluten in wheat and to the conse- 
quent milling qualities of the grain and baking qualities of the 
flour. According to Snyder, the most valuable wheats for bread 
making purposes are those in which 80 to 85 per cent of the 
protein is gluten and the gluten is composed of from 60 to 65 
per cent of gliadin and 35 to 40 per cent glutenin. 

Wheat straw has little value to the stock feeder except as lit- 
ter. Experiments have shown that when consumed it leaves 
little surplus of food value to the animal above the energy re- 
quired for mastication and digestion. But when the straw is 
pulped by the process commonly used in paper making, the 
residual tissue has been shown to have a food value equal to that 
of starch. The plant food in the straw should be saved by utiliz- 
ing it as litter or composting in the manner already described. 

Rye, like wheat, is sowai chiefly in the fall. It closely re- 
sembles the latter in its compovsitiou and habits of growth. The 
growth of this crop in early spring may be stimulated by adding 
100 to 150 pounds of nitrate of soda per acre. 

Rye grain is slightly lower in fat and protein than is Avheat. 
Its gluten is not so well suited for bread making as that of wheat, 
but rye flour produces a coarse bread which is consumed to 



i 



Cro'ps. 183 

considerable extent. The straw of this crop is high in fibre and 
the nutrient compounds which it contains are less digestible than 
those of oat or barley straws, so that it possesses little feeding 
value. 

Barley has been developed into many varieties, which fall 
mostly into either the two rowed or the six rowed type. It may 
be sown in the fall and wintered, but it is more distinctly a 
sprin^i' crop than is rye or wheat. It is hardier than the latter, 
being adapted to wider ranges of latitude and climate. The 
crop grows rapidly and is more exhaustive of surface soil miner- 
als than the cereals already discussed, because of the limited feed- 
ing area of its root system. This limitation, together with its 
comparatively short period of growth, makes the crop more de- 
pendent upon liberal manuring than are wheat or rye. Spring 
tillage, however, aids nitrification and reduces the requirement 
for available nitrogenous manures. Its comparatively limited 
root system and short time of growth makes it especially respon- 
sive to soluble phosphate manuring. Excessive supplying of 
nitrogen to this crop is to be avoided, not only because of the 
coarse rank growth which it induces at the expense of seed pro- 
duction, but also, because the high protein content of the grain, 
consequent upon such manuring, unfits it for malting purposes. 

Barley is richer than wheat in ash, fibre and protein; the 
former two constituents are largely contributed by the hull 
of this grain. It is slightly poorer in fat and carbohydrates than 
is wheat. Barley gluten does not possess the property required 
for bread making, and consequently the grain finds only a lim- 
ited use for human food. It is fed to horses and cattle and is 
highly esteemed for the production of pork. 

The production of malt from barley gives this grain its chief 
value. To produce this, the grain is soaked in water for some 
time and spread upon floors in thick layers. Germination en- 
sues and heat is evolved in the process. When the sprouts are 
about one-half inch long, the grain is heated sufficiently in an 



184: Agricultural Chemistry. 

oven to kill the embryo. The sprouts are then removed, dried 
and ground, and put upon the market as a feeding-stuff under 
the name of ''malt sprouts." The remaining grain, known as 
"malt," does not differ much in composition from the original 
barley ; but the germinating process has produced and activated 
an enzyme of the seed, knowTi as "diastase." If the malt is 
heated now with water for some time at 120° F., a process known 
as ' ' mashing. ' ' this enzyme converts the starch of the grain into 
soluble carbohydrates. Diastase has been found capable of thus 
transforming 2000 times its own weight of starch into dextrines 
or maltose. Since the amount of this enzyme in barley is capable 
of transforming much more starch than is associated with it, 
unmalted barley or other starchy grains, such as corn, are fre- 
quently added to the mash. The maltose produced in this man- 
ner, together with other substances, is dissolved in the liquor of 
the mash and may be drawn off and seeded with the proper yeast 
to undergo alcoholic fermentation. This fermentation results 
in the production of beer and other liquors. 

The residual grain, which contains the fat and protein orig- 
inally present, is jjlaced upon the feeding stuff market as "wet 
or dried brewers' grains." The latter form is preferred for 
its more economical handling and better keeping qualities. 

Barley straw, when used in feeding experiments, has been 
shown to be more completely digested by ruminants than is the 
straw of wheat or rye, thus giving it a limited value for feeding 
purposes. This fact has also been demonstrated by practice. 

Oats is also a crop which spring sowing and tillage aids. 
The spring tillage, in preparing the land for sowing, acts as an 
aid to nitrification and makes it unnecessary to apply the directly 
available nitrogenous fertilizers. But its short gro's\ang season 
renders it dependent upon liberal manuring to produce max- 
imum yields. Excess of nitrogenous manure should be avoided 
because of the disastrous results from over-development of the 
foliage of the crop. J\Iuch of the "lodging" of nat crops on 



Cro"ps. 185 

heavy soils is probably due to excessive production of nitrates 
from humus or manure, which induces a rank growth of weak- 
stemmed plants. 

Oat grain consists of approximately 70 per cent kernel and 
30 per cent hull. The large proportion of hulls accounts for the 
high fiber and ash content of the grain and reduces its digest- 
ibility. On the other hand it appears to be of value for its 
mechanical, laxative effect upon the digestive tract. This grain 
is notable among the cereals on account of its high content of 
fat. The ground, hulled kernels, known as "oatmeal," is much 
used for "breakfast foods." The residual grain and poorer 
kernels are worked into oat feeds. Whole oats is much prized by 
the horse feeder. It has been supposed that the grain possesses 
peculiar tonic properties, due to a specific compound, but there 
are no scientific data in support of this view. 

Oat straw is more palatable than the other cereal straws and 
possesses some value as a food for cattle and sheep. 

Com, or maize, has formed over 50 per cent of the acreage 
of cereals in the United States for several decades. In 1900 it 
formed 56 per cent of the value of cereals and 28.5 per cent of 
the value of all crops. The white man discovered it under cul- 
tivation by the American Indian and gave to it the name Indian 
com. Continuous breeding has developed many improved va- 
rieties, which differ widely in size, form, color and chemical com- 
position. The common varieties of com fall under three sub- 
species : dent, flint and sweet com. By far the greatest number 
of varieties are of the dent species. This species derives its name 
from the characteristic indentation of its crown, due to shrinkage 
of the starch cap as the grain dries. Flint corn is characterized 
by a smooth, firm coat, supported by a layer of hard or horny 
starch, so that the grain retains its shape as it dries. Sweet corn 
is characterized by a high percentage of sucrose and develops a 
prominently wrinkled surface, as a result of shrinkage in drying. 

Examination of a longitudinal section of a com grain made 
by splitting it across the thin dimension, shows it to consist of 



186 Agricultural Chemistry. 

four prominent parts, as follows: — germ, light colored starch 
cells, dark gluten layers and a thin outer coating. The germ is 
located at the tip of the kernel and is more or less completely 
surrounded by starch, which forms the floury portion of the, 
grain. Outside the starch, nearly or completely surrounding it 
and more or less blending with it, is the yellowish gluten layer. 
The whole kernel is coverd hy a thin coating which forms ;i small 
amount of bran in the milling process. The germ contains most 
of the fat of the corn grain, while the gluten is the portion richest 
in protein. That portion of the starch bordering upon the gluten 
layer differs in character from the common, floury starch, and is 
known as "horny" or ''glossy" starch. Almost all of the starch 
of popcorn is of this variety. 

Corn is slightly lower in protein and much higher in fat than 
is wheat. The latter constituent is sometimes separated from the 
grain on a commercial scale as corn-oil. Corn meal is low in 
fiber and pentosans, the carbohydrates being nearly limited to 
starch. As a result, corn is used extensively in the production 
of sugar by the process already described under "glucose," the 
commercial product being kno^^^l as "corn syrup." The residue 
from this process is sold for stock feeding as ' ' gluten feed. ' ' To 
a limited extent, it is also separated into such fancy feeds as 
"corn bran," "gluten meal" and "germ oil meal." 

The corn grain is low in ash, containing but 1.5 per cent, and 
extremely deficient in lime ; this constituent forms only about 
2.3 per cent of the ash. or 0.03 per cent of the grain. It is thus 
apparent that corn alone forms an incomplete ration for grow- 
ing animals using grain alone, such as swine. 

Corn is a shallow rooted crop and requires liberal manuring. 
It has the advantage, however, of a late summer growth, so that 
it has the opportunity of assimilating the nitrates produced dur- 
ing the hot season. Fresh farm manure should be applied to 
corn, as to most of the cereals, at the rate of 8 to 10 tons per acre. 

Rice has been estimated to be the chief food of over one-half 
of the human race. It differs from the other grain crops in re- 



Crops. 18T 

quiring a warm climate and abundance of water, hence it is 
usually gro\^Ti under irrigation. When so grown it yields two 
crops and requires liberal manuring. Since nitrification is sup- 
pressed on rice land, nitrates are very effective with this crop. 
Composted manures are used for the crop in China and Japan. 

Rice grain is extremely low in ash, fiber and fat, and contains 
but about 7.4 per cent of protein. It is essentially a carbohyd- 
rate food, nearly 80 per cent of it being starch. The rice of 
commerce is a product of a milling process which removes the 
outer husk from the grain and yields as by-products, rice polish 
and rice bran. The former is fine and floury and much richer 
than the grain in ash, protein and fat, while the latter is a coarse 
material high in percentages of ash and fiber. The two by- 
products are usually mixed and sold as rice-meal, or rice-feed. 
Like wheat, and in contrast to most of the other grains, rice car- 
ries a large share of its phosphorus compounds in the outer 
coatings, which makes possible a considerable recovery of phos- 
phoric acid with the manure produced from rice feeds. 

Leguminous seeds differ chiefly from the seeds of cereals by 
a higher content of protein and a correspondingly lower content 
of carbohydrates. This does not involve, as already pointed out, 
a heavy demand upon the soil supplies of nitrogen. Protein 
formation in these crops, however, places a considerable tax upon 
the ash constituents of the soil. In some cases the carbohydate 
material of these grains has been found to consist chiefly of 
galactans, a class of compounds already discussed under the 
" poly-saccharides " of the plant. Liberal supplies of phosphoric 
acid, lime and potash are required for these crops. A number of 
legumes produce seed which form a considerable bulk of the total 
crop. This is true of the soy-bean, horse-bean and cowpea. The 
several varieties of the true bean and the pea are the only seeds, 
however, of much commercial importance. The soy-bean and 
peanut seeds are distinguished by high percentages of fat, 
amounting to about 17 and 45 per cent in the grains, respectively. 



188 Agricultural Chemistry. 

Beans thrive best on clayey soils, well stocked witli lirae/potasli 
and phosphoric acid. Several varieties are consumed, green or 
mature, as vegetables and are valued for their high protein con- 
tent. The soy-bean was introduced from Japan and soy-bean 
meal finds some use as an animal feeding-stuff. It resembles the 
bean in its habits of growth. 

Peas require much lime, and on rich soils they tend to produce 
luxuriant vines at the expense of seed. The fresh seed is prized 
as a vegetable and cured peas are valuable for pig feeding. It 
may be said that the leguminous crops in general thrive on soils 
poor in nitrogen but well supplied with the other elements of 
fertility. 

Cotton-seed is one of several miscellaneous seeds of agricul- 
tural value. The seed is enveloped by the lint of the pod, or 
"boll," of the plant. American cotton yields about 300 pounds 
of lint and 600 pounds of seed per acre. The seed is rich in 
phosphoric acid, nitrogen and potash and the crop requires ma- 
nurial applications of these constituents in the order given. Cot- 
ton-seed oil is extracted from the seed by pressure and also by the 
use of naphtha as a solvent. The outer coating, or hull, of the 
seed is generally removed previous to pressing, in which case the 
residue is known as ''decorticated cotton cake," or, when ground, 
as "cotton-seed meal." A high proportion of hulls produces a 
dark colored meal and lowers its digestibility and food value. 
The meal is somewhat valued for feeding because of its high pro- 
tein content, but because it contains some toxic substance, its use 
is necessarily restricted. It is also used as a fertilizer, supplying 
nitrogen in a form gradually available to the crop. Incidentally, 
it supplies considerable amounts of potash and phosphoric acid. 

Flax seed, or linseed, thrives under much the same environ- 
ment as that required by wheat. Where grown for fiber, the 
crop requires a moist, temperate climate, such as is found in Ire- 
land, the northern United States and Canada; but seed pro- 
duction requires warmer climates. The crop produces an ave- 



Cro^s. 189 

rage yield of about 850 pounds of seed and 2000 pounds of straw. 
Flax requires considerable amounts of phosphoric acid, potash 
and lime, with sufficient nitrogen to induce vigorous growth. 

Linseed resembles cotton-seed in composition, but contains 
about one-half as much fiber and about 10 per cent more fat, 
having 30 to 40 per cent of the latter ingredient. The oil is 
obtained as from cotton seed, the ground residue from the crush- 
ing method being known as ''old process" linseed meal, or "oil 
meal," while that obtained by solvents is known as "new pro- 
cess" meal. "Old process" meal carried 8 to 12 per cent of fat, 
while the new process of extraction leaves only 2 to 4 per cent 
of this constituent. The oil obtained from flax seed of the region 
about the Baltic Sea in Europe is preferred in the paint industry 
because of its great absorbing power for oxygen. Linseed meal 
is a valuable high-protein food for stock. 

Hempseed is obtained from a crop resembling flax in its utility 
both for fiber and seed. It grows best in a temperate climate 
and resembles corn in its requirements of the soil. Hemp yields 
500 to 1500 pounds of fiber and the same range of seed per acre. 
The seed is used as poultiy food and the oil obtained from it 
is sometimes used to adulterate linseed oil. 

Buckwheat has much the same composition as wheat. It has 
the advantage of thriving upon comparatively light, poor soils. 
It finds limited use in animal feeding and as human food. 

Rape seed is sometimes grown for the production of "rape 
oil" or "colza oil." .It yields over 40 per cent of this fat. The 
residue of the feed is used as manure, because it lacks relish as 
a cattle food. Rape belongs to the same plant family as the 
turnip and closely resembles it in manurial requirements. 

The castor bean is the seed of a plant grown in some local- 
ities as a crop, in others for ornamental purposes, while in some 
cases it is looked upon as a. weed. In the temperate zone it is 
an annual, but in the tropics it is a perennial tree of considerable 
size. It is an adaptable plant but thrives best on rich, sandy 
soils. The seed is valued for oil, which it contains to the extent 



100 Agricultural Chemistry. 

of 50 per cent. This oil finds application medicinally and as a 
lubricant. The residue of the seed is suitable for manure, but 
cannot be used for feeding because of its poisonous properties, 
due to a powerfully toxic protein, known as ''ricin." 

Sunflower seed is produced in yields of about 50 bushels per 
acre. The dry seed contains 20 per cent of an oil sometimes used 
as a substitute for olive oil. It also contains 30 per cent of fiber 
and ] 6 per cent of protein, the latter giving to the seed and its 
residue some value as poultry and cattle feeds. The crop pro- 
duces heavily on soils high in fertility. 

Hays or fodder crops include true hays which are cut at the 
blossoming or early seeding stage, and in which the stems so pre- 
dominate in bulk as to make them practically straAv crops. They 
have, in fact, the same general composition and food require- 
ments as the cereal grains, irrespective of seed production. Un- 
der this class also fall the cereal grains, such as barley or oats, 
when cut while succulent for soiling purposes or hay making, and 
com and other crops cut for silage. These differ from the cereal 
straws as a result of their comparative immaturity. The leg- 
uiuinous plants in this role differ from the corresponding legumes 
raised for seed in the same manner as indicated for cereal plants. 
They are cut at an immature stage of growth when the foliage 
far outweighs the seed in amount and importance. The true 
hays of importance are comparatively few in number. 

Timothy is perhaps most commonly grown, alone or associated 
wuth clover. It is representative of the true grasses, as a class, 
being high in fiber, comparatively low in protein, and rich in 
potash and silica. It is shallow rooted and dependent upon 
liberal manuring. It grows best on peaty soils and hence is fav- 
ored by hea^y applications of farm manure. The application 
yearly per acre of 90 to ] 80 pounds of nitrate of soda, 300 to 600 
pounds of bone meal and 70 to 140 pounds of chloride or sulphate 
of potash has been recommended as a fertilizer treatment. 

Red top, Hungarian grass, Kentucky blue grass or June 
^rass, orchard grass and similar hay crops resemble timothy in 



Crops. 191 

their feeding habits and composition and require similar manur- 
ing in proportion to their yield. 

Meadow hay and pasture grass are usually a mixture of 
plants, the predominant members of which are among the grasses 
already described, or others closely related to them. The peaty 
nature of the surface soil in permanent meadows is attributed to 
the decay of the shallow seated root system. This condition fav- 
ors nitrification, which tends to exhaust the lime by the leaching 
of nitrate of lime from the soil. Such crops are therefore gen- 
erally responsive to applications of lime, which may either be 
applied as limestone, burned lime, or in combination with phos- 
phoric acid, as basic slag. Heavy dressings with farm manure 
or commercial fertilizers tend to drive out the valuable clovers 
and other leguminous plants and replace them mth coarser 
growths. This is partly due to the production of an acid soil, 
which may be restored to normal condition by applications of 
wood ashes or lime. Yearly applications of plant food should be 
made to these permanent crops. 

Cereal hays are made by cutting the crop when the grain is 
in the milk stage and just preceding the most active migration 
of nitrogen and ash constituents to this part of the plant. The 
nutrient compounds are then distributed generally through the 
plant and their digestibility is less depressed by cellulose com- 
pounds than is the case at maturity. The maximum production 
of tissue, especially desirable with these crops, will be promoted 
by liberal applications of nitrogen oils manures. 

Barley, oats, millet, sorghum and other cereals, which produce 
the more nutritious straws, are utilized for hays. They may be 
made to produce enormous yields, but at the expense of much 
plant food. Under such conditions, they must be considered as 
particularly exhaustive crops requiring heavy manuring. 

The leguminous hays, while comparatively independent of 
manurial supplies of nitrogen, are sometimes benefited in early 
stages of growth by the application of soluble forms of nitrogen. 
This produces a plant of increased vigor and promotes further 



192 , Agricultural Chemistry. 

assimilation of food. These crops feed heavily upon lime, potash 
and phosphoric acid. This fact is to be attributed largely to 
their extensive root systems, drawing from a wide range of soil 
for a large production of dry matter. As a consequence, these 
crops are especially benefited by the inorganic constituents of 
manures. 

The reappearance of clover in limed meadows is a commonly 
observed indication of the value of this fertilizer. "Wood ashes 
benefit these crops chiefly by reason of their content of lime and 
potash. The following fertilizer ration per acre has been re- 
commended for clover and alfalfa: 40 pounds of nitrate of soda 
or 1 ton of farm manure ; 500 pounds of bone meal ; 150 pounds 
of muriate or sulphate of potash, or 1500 pounds of wood ashes ; 
1 to 3 tons of ground lime-stone, as required. 

Ensilage is properly a hay crop. It is principally prepared 
from com, although sorghum, millet, clover, cow peas and other 
succulent crops have been so treated. The production of good 
silage depends upon careful exclusion of the air. Under this 
condition the mass undergoes changes involving the consumption 
of oxygen and production of compounds not previously existing 
in the fresh material. The temperature of the mass rises and 
reaches its maximum in two or three days. These changes were once 
thought to be due chiefly to organisms producing alcohol, lactic 
and acetic acids, and other products of fermentation. Babcock and 
Russell, as a result of their studies on silage, have concluded that 
bacteria are not the essential cause of the changes within the silo, 
but are probably deleterious and exert their influence only in the 
production of objectionable putrefactive changes. These in- 
vestigators further conclude that the changes in the silo are 
chiefly due to the respiration of living plant cells. This process 
either may involve the oxygen confined in the air spaces of the 
ensiled material, in which case it is known as "direct respira- 
tion," or it may utilize only the oxygen of compounds in the 
plant tissue, this process being kno'WTi as ' ' intra-molecular respir- 
ation. " Both forms of activity cease with the death of the plant 



Crops. 193 

cells. Hence, the more mature the corn when ensiled, the sooner 
these changes and the losses incident to them, cease. This theory' 
is in harmony with the practical experience that rather mature 
com produces superior ensilage. Maximum yield of material 
and the production of good silage are secured by selecting the 
corn when in a glazed state. 

Chemical changes in the silo entail a loss of dry matter, the 
amount of which is dependent upon the care with which air is 
excluded. In the majority of cases investigated this loss has 
been from 15 to 20 per cent of the dry matter of the fresh crop 
and in some cases it has reached 40 per cent. King states that 
the loss need not exceed 4 to 8 per cent for corn and 10 to 18 
per cent for clover. In 64.7 tons of silage packed in a silo, tight- 
ly lined with galvanized iron, he found an average loss of 6.38 
per cent. The loss was estimated for eight separate layers in the 
whole silo and found to be 32.53 per cent for the top layer, 23.38 
per cent for the next, and from 2.1 to 10.25 per cent for the 
others. The greater loss for the more exposed layers emphasizes 
the importance of oxygen in effecting a loss of dry matter, and 
the need of excluding air from the material by tightly packing it. 
In properly cured silage the loss of dry matter falls chiefly upon 
^sugars, which are oxidized to organic acids and ultimately to 
carbon-dioxide and water. A part of the protein compounds is 
also altered, with the production of amino acids. In some cases 
over one-half of the nitrogen of the silage is present in the latter 
form. This is two to three times as much as the original fodder 
contains. 

Since the sugars and proteins are compounds of high food 
value, the importance of restricting such losses in the silo is evi- 
dent. Jordan estimates that a saving of three-fourths or even 
of one-half the average losses from 100 tons of com as silage, 
would increase the farmers' food resources by an amount equiv- 
alent to from 5 to 1^2 toiis of timothy hay. 

Root crops are generally gross feeders and quite dependent 
for their food supplies upon readily available materials. 



194 Agricultural Chemistry. 

The turnip is a biennial plant which stores food the first season 
and produces seed the second year. The several varieties differ 
chiefly in the form and color of the root. The common turnip 
contains about 8 per cent of dry matter, which is largely starch. 
The rutabaga, or Swede turnip, contains more dry matter (about 
13 per cent) and about 10 per cent of carbohydrates. The lower 
content of water than in the turnip promotes better keeping 
(lualities. Turnips require an abundance of nitrogenous fer- 
tilizer. Investigations in this country indicate that the turnij) 
family is less dependent upon readily available forms of phos- 
phoric acid than other crops. 

The beet is cultivated in several varieties. It is a deeper 
feeder than the turnip by virtue of its longer tap-root. The com- 
mon red beet contains about the same proportion of dry matter 
and nutrients as the rutabaga. Mangel-wairzels, or field beets, 
are somewhat poorer than the red beet in dry matter, and notice- 
ably so in nitrogen-free extract. The mangel produces a large 
root containing about 12 per cent of dry matter. The sugar beet 
is a smaller variety of the mangel. It contains more dry matter 
(13 to 19 per cent) than the other roots, most of which is sucrose. 
The production of beet sugar in Europe alone for 1903-190-1 was 
estimated at about six million tons, or nearly twice the world's 
production of cane sugar. These root crops do best on deep, 
loamy soil, in rather wami, damp seasons, except that the mangel 
and sugar beet require rather dry fall weather. Mangels are 
probably the most exhaustive farm crop and require heavier ma- 
nuring than the other roots, 12 to 14 tons of manure per acre 
being a common application. They are less dependent than 
turnips upon phosphate fertilizers, but respond generously to 
applications of nitrate of soda (about 200 pounds per acre). 
This crop is also benefited by the addition of common salt. The 
production of large roots is sometimes objectionable because they 
contain much more water than small ones. This is true \vith the 
sugar beet, where a high production of sugar is desired. Heavy 
manuring is therefore avoided and the crop is thickly sown. The 



Crops. 195 

following manuring per acre is recommended for sugar beets: 
3 tons of stable manure, 300 pounds of acid-phosphate, 140 
pounds of sulphate of potash. The soil should be fairly stocked 
with lime. 

The potato is a surface feeder and must be liberally manured 
to secure good yields. This crop contains 20 per cent of dry 
matter, which is mostly starch. It is a staple human food and 
is also fed to stock. In Europe, one of the principal uses for 
the potato is for the manufacture of alcohol. Stable manure 
appears to favor growth of scab and should be applied to a pre- 
ceding crop. Chloride of potash is also said to be injurious to 
this crop. The fertilizer recommended per acre is : 225 pounds 
of sulphate of ammonia, 500 pounds of acid-phosphate and 200 
pounds of sulphate of potash. 

Fruit crops present peculiar manurial requirements, especially 
with relation to perennial growths. The composition of the 
20 per cent of dry matter in common fruits is principally of car- 
bohydrate nature (invert sugar, sucrose, cellulose, pentosans and 
pectose) with small amounts of organic acids, ash and nitrogen 
compounds. Green fruit contains starch, which is converted to 
sugar in the ripening process. The production of these com- 
pounds creates special demands for potash. Phosphoric acid 
and nitrogen are required in smaller amounts, except by the 
plum, an average crop of which removes 128 pounds of nitrogen 
per acre. The strawberry, blackberry and similar fruits will 
produce the best yields when a vigorous cane growth is in- 
duced by liberal manuring. They thus respond most markedly to 
applications of liquid manure. The fruit of trees draws its nu- 
trients from an extensive woody growth and volume of sap, but 
these sources must be reinforced to keep the trees in vigorous 
bearing condition. Light yearly applications of farm manure 
or complete fertilizers are recommended for these crops. 

Forest growth presents practically the same demands on fer- 
tility as do fruit trees, but as has been pointed out, this demand 



196 Agricultural Chemistnj. 



n 



is practically covered by a continuous return of plant food from 
this crop to the soil. 

The miscellaneous crops, grown chiefly for the truck market, 
give cash returns which justify the expense of "forcing" rations 
of plant food. Such rations should include liberal amounts of 
nitrogen. Tobacco should receive some nitrogen and a liberal 
supply of potash, wdth phosphoric acid in moderate amount. Too 
much nitrogen is to be avoided because of unfavorable effects on 
the quality of the tobacco leaf. Cotton-seed meal at the rate of 
200 to 300 pounds per acre before planting is a favorable ration. 
Potash should be applied as sulphate (100 lbs.), as the chloride 
is injurious. Phosphoric acid should be applied at the rate of 
200 pounds of acid-phosphate or 400 pounds of bone meal per 
acre. 

Cabbages, as a market crop, are brought to harvest early and 
are improved in quality by heavy applications of nitrogen. Nit- 
rate of soda or sulphate of ammonia at the rate of 300 pounds per 
acre in two or three top dressings is recommended in addition 
to general manuring. 

No specific rules can be laid down for the application of fer- 
tilizers to each crop, because of the greatly variant conditions of 
soil and climate under which it must be grown. These factors, 
particularly the latter, exert a profound influence on the growth 
of plants. Each farmer nuist determine the requirements of his 
own conditions by the fertilizer tests described in the chapter 
on "Fertilizers." 

Factors influencing the composition of the crop are : Stage 
of gro^^•th. exposure at hai-vest, fertilizers and environment. 

The stage of growth has been shown to present marked differ- 
ences in the feeding value of the straw of cereal plants. In the 
true hay crops the grain takes up most of the nutrients of the 
plant during the ripening period. This results in increased fiber 
content and decreased feeding value of the stems. The Connec- 
ticut Experiment Station gives the following composition of 
timothy at successive periods preceding ripening. 



Crops. 
Composition of Dry Matter of Timothy. 



197 



Stage of growth 



Ash 



Crude ' Crude ^^{^^f" Ether 
protein fiber i g^tract ' ^^^ract 



Well headed out. . . . 

In full blossom 

When out of bloisom 
Nearly ripe 



Per cent 
4.7 
4.3 
4.1 
3.0 



Per cent 
9.6 
7.1 
7.1 

6.8 



Per cent 
33.0 
33.3 
33.8 
35.4 



Per cent 

50.8 
53.3 
53.3 
52.2 



Per cent 
1.9 
2.0 

1.7 
2.0 



It will be observed that the protein and ash of the hay decrease 
rapidly from the heading out stage, while the fiber increases at 
the later stages. The nitrogen-free extract at the later stages is 
probably less valuable than at the earlier periods of growth as 
a result of increased proportions of indigestible pentosans and 
similar compounds. Thus, while the hay crops increase in the 
quantity of dry matter to the end of the ripening period, they 
decrease in palatability and food value when harvesting is de- 
layed too long. These conditions are more serious with legume 
hays, where a large percentage of protein is involved. This is 
shown in the following table on the composition of alfalfa hay 
published by the Kansas Experiment Station : 



Composition of Dry Matter of Alfalfa Hay. 



Ash 



Crude Crude ^'^{[i^f" 

protein fiber ^^^^^^^ 



Ether 
extract 



First stage (about 10 
per cent in bloom) 

Second stage (about 
^2 per cent in 
bloom) 

Third stage (full 
bloom) 



Per cent 
10.45 



10.28 
8.45 




Per cent 
32.20 

35.37 
36.10 



Per cent 
. 27.29 

34.00 
39.62 



Per cent 
1.56 

1.05 
1.41 



198 



A griculhira I Ch emistry. 



The decrease in protein at the last stage is marked. These 
data indicate that the most favorable mean between quantity and 
quality of crop will be secured by cutting grasses and clovers 
between early and full bloom. 

"With corn, conditions are different. Analyses at the Maine 
Experiment Station gave the following data: 



n 



Composition of Dry Matter of Com Plant. 



Stage of growth 



Ash 



Crude 
protein 



Crude 
fiber 







Nitro- 


Sugar 


Starch 


gen 

free 

extract 


Per 






cent 


Percent 


Percent 


11.7 




46.6 


20.4 


2.1 


55.6 


20. () 


4. it 


59.7 


21.1 


5.3 


62.5 


16.5 


15.4 


63.3 



Ether 
extract 



Very immature 

(Aug. 15) 

A lew roasting ears 

(Aug. 2«) 

All roasting stage 

(Sept. 4) 

Some ears glazing 

(Sept. 12) 

AH ears glazed 

(Sept. 21 ) 



Per 
cent 

9.3 

6.5 

6.2 

5.6 

5.9 



Per cent 


15 





11 


7 


11 


4 


9 


6 


9 


2 



Per 

cent 

26.5 
23.3 
19.7 
19.3 
18.6 



Percent 
2.6 
2.9 
3.0 
3.0 
3.0 



The material increase in starch and other digestible carbo- 
h3''drates more than offsets the relative decrease in crude protein 
and is accompanied moreover by a decrease of crude fiber. Feed- 
ing experiments moreover have shown that mature corn is more 
digestible than the immature plant, both as fodder and as silage. 

Exposure to the weather, particularly undue exposure to 
rainy weather, detracts from the value of the crop. This is due 
to the leaeliing away of nutrient compounds by the rain. 

The following table from Bulletin 135 of the Kansas Station 
shows the extent of such losses from alfalfa hay, assuming, as is 
approximately true, that no fiber is lost. The hay was exposed 
during 15 days, during which time it was subjected to three 
rains amounting to 1.76 inches: — 



Crops. 
Louses by Rain to loO Pounds of Alfalfa Hay. 



199 



Pounds in original. 
Pounds in damaged 

Pounds lost 

Per cent lost 



Crude 


Crude 


Crude 


Ash 


protein 


fiber 


12.2 


18.7 


26.5 


8.7 


7.5 


26.5 


3.5 


11.2 


00.0 


28.7 


60.0 


00.0 



Nitro- 
gen 
free 

extract 



Crude 
fat 



38.7 
23.0 
15,7 
41.0 



3.9 

2.6 

1.3 

33.3 



Total 



100.0 
68.3 
31.7 
31.7 



Not only has nearly one-third of the total dry matter been lost, 
but over one-third of this loss has fallen upon protein, which is 
the most valuable constituent of the hay. For every pound of 
protein in the damaged hay, one and one-half pounds have been 
lost by exposure. 

Curing processes may seriously affect the composition of 
crops. Alfalfa hay furnishes a striking example of this fact. 
When cut early, this crop bears 73 pounds of leaf for 100 pounds 
of stem. The leaf, however, is much richer in nutrients than 
the stem. Thus, for 100 pounds of each constituent in the stems, 
the leaves of an equivalent amount of crop in each case will 
contain of: fat, 450 pounds; protein, 250 pounds; nitrogen free 
extract, 135 pounds; crude fiber, 28 pounds. That portion of 
the crop especially subject to mechanical loss in hay making is 
therefore the most valuable as fodder. 

Headden has estimated the mechanical loss of alfalfa in har- 
vesting at 15 to 20 per cent of the dry crop. In extreme cases 
60 per cent or more may be left on the field. This loss falls 
chiefly upon the leafy tissue. More valuable hay will be secured 
if the crop is cut between early and full bloom and handled to 
a minimum extent, than if it is allowed to become brittle by aging 
or over-curing at harvest and then excessively handled. 

Fertilizers influence the composition of the crop to a limited 
extent, both by their amount and their nature. This effect has 
been observed principally with reference to the increase of pro- 



200 Agricultural Chemistry. 

tein formation by application of nitrogenous fertilizei's. Pingree 
found that nitrogen applied to oats, in the form of dried blood, 
slightly increased the protein content of both grain and straw. 
At the Storrs (Conn.) Experiment Station, corn, oats and mixed 
grass (timothy, red top and Kentucky blue grass) were supplied 
with gradually increasing amounts of nitrogen, added to a uni- 
form ration of potash and phosphoric acid. "Within certain 
limits, the protein content of the com and oat grains, oat straw, 
corn stover and grasses was increased, somewhat in proportion 
to the amounts of nitrogen supplied. Parozzani found that in- 
creased application of super-phosphates to com resulted in a 
corresponding increase of total phosphoric acid in the seed. In- 
vestigation of the distribution of phosphorus in the seed showed 
that, while the amount in nuclein compounds remained constant, 
the amounts in the forms of lecithin and phytin were increased. 
Total nitrogen in the seed was not sensibly affected, but the pro- 
portion of true protein compounds was slightly increased and 
this increase was limited to a specific protein, namely, zein. 

Such examples as these are limited. From an intimate knowl- 
edge of the long series of fertilizing experiments at Rothamsted, 
Hall is led to state that, ''Although the composition and quality 
of the grain is affected by the amount of nitrogen supplied to the 
crop, it is really astonishing to find how small are the changes 
brought about by extreme differences in manuring." The effects 
may be more marked with other parts of the crop, but, quoting 
Hall further: "The crop reacts against variations in the com- 
position of the soil and tends to keep its o\mi composition con- 
stant. When also the time comes for the grain to be formed 
from the reserve materials already stored up in the plant, an- 
other attempt is made to turn out a standard product. Even on 
the Rothamsted p^pts, where the differences in the supply of 
nutrients are extreme and have been accumulating for 50 years, 
the composition of the grain changes more from one season to 
another than it does in passing from plot to plot." 

Environment has been found to influence the composition of 



Crops. 201 

the crop mojrc than any other factor. The sugar beet has given 
valuable results along this line in experiments, conducted by 
Wiley in this country from 1900 to 1905. Beets were grown 
from the same seed at 12 experiment stations scattered from 
Kentucky to Wisconsin and from New York to California. At 
Utah, California and Colorado the crops were grown under ir- 
rigation. Chemical and meteorological records were carefully 
kept in all cases. As a result of this and similar investigations, 
Wiley concludes that the soil and fertilizers have only a limited 
influence and that temperature (or latitude) is the most potent 
element of the environment in the production of a beet rich in 
sugar. Excessive rain fall and irrigation affect the beet only in- 
cidentally by increasing the yield with a proportionate reduction 
in percentage of sugar, and dry tillage produces opposite effects. 
With these conclusions as a basis, there has been mapped for the 
northern United States a belt of country which presents optimun 
climatic conditions for the production of sugar beets. 

Wheat has been tested in a similar manner and the results 
have been reported recently by Le Clerc. Crops were grown 
from the same seed at the apices of two great triangles ; namely : 
Kansas, South Dakota and California; and Kansas, Texas and 
California. The results demonstrate that the same variety of 
wheat brought from different localities and grown side by side in 
one locality, yields crops of almost the same appearance and com- 
position. On the other hand, "wheat of any one variety from 
any one source and absolutely alike in chemical and physical 
characteristics, when grown in different localities, possessing dif- 
ferent climatic conditions, yields crops of very widely different 
appearance and very different chemical composition." Thus, 
with relation to protein, the constituent of most concern, the 
seed of Kubanka wheat grown in South Dakota in 1905 contained 
13.03 per cent. The 1906 crop grown from this seed contained : 
in Kansas, 19.85 per cent of protein in the seed, in California, 
9.68 per cent, and in South Dakota, 14.24 per cent. The seed 
from these localities grown in 1907 at California contained 9.70, 



202 AgHcultural Chemistry. 



9.00 and 9.05 per cent of protein in the seed, respectively, while 
portions of the same seeds grown in South Dakota contained 
14.24, .13.89 and 12.87 per cent of protein. The same condition 
obtained with Crimean wheat grown in the other triangle, Kansas 
uniformly producing the highest protein content in the grain 
and (yalifoniia the lowest. These results lead to the conclusion 
that a crop should be improved by selection in the region where 
it is to be grown, or that "seed should be selected from a region 
of similar climatic condition." 

The author just quoted compared eight samples of Durum 
wheat grown in arid and semi-arid regions \\\ih. seven samples 
of the same variety from hiunid regions. The seed from dry 
regions contained 17.23 per cent of protein, and that from humid 
regions, 13.75 per cent ; and the samples weighed 30.3 grams and 
33.5 grams per 1000 grains, respectively. Abundant water sup- 
ply is thus productive of plump, starchy grains, while dry con- 
ditions produce a smaller grain richer in protein. This contrast 
is illustrated by the change in composition of Dunim wheat 
grown in Mexico. The original seed contained 12.3 per cent pro- 
tein. Gro^^^l under irrigation it produced seed of 11.1 per cent 
protein, non-irrigated, 17.7 per cent. Shutt has confirmed these 
data with wheat grown on irrigated and non-irrigated soil at 
Manitoba, Canada. Lawes and Gilbert had previously observed 
at Rothamsted that hot, moderately dry seasons produced the 
best quality of wheat. 

Sweet corn has been similarly' tested by Wiley for several suc- 
cessive years. The results have shown that the content of sugar 
is less influenced by temperature than in the case of the sugar 
beet. The ripening crop was followed along the Atlantic coast 
from Florida to Maine. Contrary to the results with the sugar 
])eot the higher average content of sugar appeared to be found 
in the warmer climates. The lower temperatures of the North, 
however, retard the ripening process and render the com suc- 
culent for a longer period than does the warm climate of the 
extreme South. "Wiley concludes that the amount and distribu- 



m 



Crops. 203 

tion of rainfall is the most important factor affecting the edible 
quality of green sweet com. and that the favorable effects of 
moderate, well distributed rain-fall indicate that the northern 
states will continue to produce the best crop outside the irrigated 
districts. But no special area for sweet-corn growing can be 
mapped as has been done in the case of the sugar beet. 

Crop rotation should be rationally based upon the varying de- 
mands of crops for plant food and the characteristic feeding 
habits of individual species of plants. "When the plant food of 
the surface soil has been exhausted by such shallow rooted crops 
as corn, grasses and turnips, they should be followed by deep 
rooted crops, such as wheat, mangels, or alfalfa. Not only will 
the latter crops obtain their supplies of food from the lower 
layers of the soil, but they leave a portion of it at the surface 
in roots and stubble, from which it becomes available to succeed- 
ing crops. No more striking example of this fact is furnished 
than that of alfalfa. According to Headden, the roots and stub- 
ble of alfalfa to a depth of G^i/o inches contain approximately 
2.86 tons of dry matter per acre, having the following constit- 
uents: total ash 172 pounds; phosphoric acid 24 pounds; sulphur 
trioxide 9 pounds; lime 50.5 pounds; chlorine 6.5 pounds; mag- 
nesia 3 5.15 pounds; potash 44.5 pounds; and 104 pounds of ni- 
trogen. Reference to the table in the Appendix which gives 
"Plant food removed by crops," shows that the stubble of al- 
falfa alone, places in the surface soil as much plant food as is 
removed by total cereal crops. 

The waste tops of the mangel crop can also restore to the 
soil as much food as is required by an average grain crop. Not 
only will these crops restore fertility to the surface soil, but their 
deep root systems, and the deep thorough tillage demanded by 
them, will benefit the physical condition of the soil when they 
are grown in rotations. 

Increase of soil nitrogen is the most valuable effect produced 
by legume crops grown in systems of rotation. In this connec- 
tion the work of Shutt in Saskatchewan, Canada, is of interest. 



204 



Agricultural Chemistry. 



Tie compared a virgin soil of that province Avith one that had 
been continuously cultivated to cereal grains or fallow for 20 
years. The cultivated soil contained 0.253 per cent of nitrogen 
(to a depth of 8 inches) and the virgin soil contained 0.371 per 
cent. This difference represented a loss of 2200 pounds of nitro- 
gen per acre by the system of cultivation practiced. Investi- 
gating the possibility of restoring nitrogen to the soil, Shutt grew 
common red clover upon a poor sandy soil, cutting the crop twice 
yearly and leaving it upon the soil. At the end of each second 
season the crop was turned in and the plot re-sown the next 
spring. In five years of this treatment the soil gained over 300 
pounds of nitrogen per acre to a depth of four inches, despite 
inevitable losses by nitrification and leaching. 

The effect of the growth of clover on succeeding crops was 
demonstrated by Shutt in field experiments. Two series of plots 
were used, on one of Avhich clover was compared with wheat, 
while on the other oats and clover were compared with oats. 
The first series will be described. On one plot, clover was sowi\ 
alone and one cutting made and removed. The crop was turned 
under in the following spring. On the other plot, wheat was 
grown and harvested as usual. The effect of this treatment was 
observed on grain and root crops for three succeeding years, with 
the following resultant data : — 



Increase of Crop 


Due to Growth of 


Clover. 




1900 


1901 


Lbs. 


1902 


1903 




1 
Tonp 


1 Bush. 


Lbs. 


1 1 

j Tons Lbs. 


Plot A: Clover 

PlotB: Wheat 

1 net ease due to clover 


Corn 
Corn 
Corn 


27 
10 

8 


1,760 

1,280 

480 


Oats 
Oats 
Oats 


75 10 
51 26 
23 , 18 


Supar 
beets 


22 600 

8 1,260 

13 1,340 



Crops. 



205 



This effect was obtained without a sacrifice of the crop and 
must have been chiefly due to the nitrogen supplied by the stub- 
l)le and second growth of the clover. 

The distribution of nitrogen in the legume crop bears an im- 
portant relation to its proper use in rotations. Shutt gives the 
distribution of nitrogen between the roots and stubble and the 
tops of legumes as follows: — 



Nitrogen in Legumes. 



Legumes: One season's growtli 


Nitrogen in parts of crop 
(Poimds per acre of crop) 


J . In 9 in. depth of 
1 11 tops root and stubble 


Clover, common red 

Clover, mammoth 

Clovpr crimson 


90 
82 
85 
75 

129 

82 

- 63 

119 


48 
48 
19 


Alfalfa 


61 


Hairy Vetch 

Sov bean .... ~ 


18 
13 


Horse bean 


15 


Pea 


10 







The proportion of the total nitrogen of the crop contained in 
the roots of common red and mammoth clovers and alfalfa in- 
dicate the effectiveness of the residues of these crops as sources 
of nitrogen, when they are grown in rotations and the crop 
hai^ested. The figures for alfalfa are probably much below the 
average and fail to do justice to the crop. The condition is dif- 
ferent with shallow rooted legumes. Thus, with the vetch and 
pea, a large supply of nitrogen in the tops is correlated with a 
comparatively small amount in the roots. Marked benefit from 
these crops in rotations can be secured only where the whole 
growth is turned in. Snyder states that the nitrogen content 
of the soil can be maintained and even slightly increased when 
clover is grown two years in a five course rotation with grjiins 
and timothy to which farm manures are applied. 



CHAPTER IX 



THE ANIMAL BODY. 



The elements found in animal tissue are the same as those 
found in the plant world, and while sodium and chlorine are con- 
sidered by some as non-essential for plant development, in the 
formation of the animal's tissue they are indispensable. Fluor- 
ine and silicon are also always found in the animal body, but 
are not known to be absolutely essential for life or growth. 
Fluorine occurs in small quantities in the teeth and bones, and 
silicon in the hair, wool and feathers. 

The compounds forming the animal body are many and very 
complex and only a brief survey of the principal ones can be 
given here. 

The constituents of the animal body may be divided into: — 

(1) Inorganic compounds, including water, various acids and 
numerous salts ; some are in the solid state, as the calcium phos- 
phate of the bone ; others are in solution as the sodium chloride 
of the blood. 
(2) Organic compounds, 



Siraple-prnteins, 
amino-acids, etc. 

1 


Coujugated-proteins 


Derived 
proteins 


(a) NitroT:enous 

(b) Non-nitrogenous. . . 


Albumins 

Globulins 

Albuminoids 

Amino-acids 

Amides 

Fats 
Carbohydrates 


Nucleo-proteins 
Phospho proteins 
Glyco-proteins 


Proteoses 
Peptones 



Of the inorganic constituents, by far the largest part is con- 
tained in the bones. In fat animals 75 to 85 per cent of the 
total ash constituents of the bodv are found in the bones. Bono 



The Animal Body. 207 

ash consists of phosphate of calcium, with a small quantity of 
carbonate of calcium and phosphate of magnesium. In muscle 
by far the most abundant ash constituent is phosphate of potas- 
sium. Potassium salts are also abundant in the "yolk" of un- 
washed wool and in the sweat of horses and other animals. Blood, 
on the other hand, always contains a preponderance of sodium 
salts. 

The nitrogenous substances constituting the animal body are 
extremely varied in character and properties and it would be 
impossible in a book of this kind to attempt to describe them in 
detail. The albumins and globulins form the substance of ani- 
mal muscle and nerve, and the greater part of the solid matter 
of blood. They are undoubtedly of the greatest importance in 
the animal economy. The albuminoids form the substance of 
skin and sinew, of all connective tissue, and also the protein 
material of cartilage and bone. Keratin, the principal protein 
of horn, hair, wool and feathers, belongs to this class. The re- 
markable difference in the properties of the protein, keratin, and 
the protein, serum-albumin, lies in the internal structure of their 
respective molecules. 

The nucleo-proteins always contain phosphorus and are con- 
tained in every cell. They are of special importance in all life 
processes. The phospho-proteins are represented in the animal 
kingdom by the important nitrogenous body found in milk, 
namely, casein. This class of bodies is also represented in the 
yolk of the egg, in the form of the protein, vitellin. These phos- 
pho-proteins contain phosphorus just as the nucleo-proteins do, 
but differ in their internal structure from those bodies. The 
glyco-proteins are compounds of a protein molecule with a sub- 
stance, or substances, containing a carbohydrate group. In 
solution, they are characterized by being ropy and mucilaginous 
and are contained in the mucus secretions of many membranes 
and glands of the animal. 

The proteoses and peptones are found in the digestive tract of 
the animal and are derived from the proteins of the food by the 



208 Agricultural Chemvitry. 



^ 



action of the proteolytic enzymes of the alimentary canal. They 
are -water-soluble bodies. 

All of these protein bodies contain very similar amounts of 
nitrogen — namely, ] 5 to 18 per cent. Besides the above nitro- 
genous materials constituting tissue, the animal juices contain a 
variety of nitrogenous substances such as creatin, creatinin, sar- 
cosine, etc., but with which we are not concerned. 

The amino-acids are simple nitrogenous bodies formed during 
the process of digestion from the proteins of the food and are 
believed to be the building materials out of which the animal 
reconstructs its own tissue protein. 

The amides, principally represented by urea in the urine, are 
the simple nitrogenous waste products of the tissues. In the 
cow, 85 to 95 per cent of the total nitrogen in the urine is in this 
form. 

The fats occurring in the animal body are principally stearin, 
palmitin and olein. Stearin predominates in hard fats and olein 
in more fluid fats. They are identical in composition with these 
same materials described in the chapter on the plant. Lecithin, 
a complex fat containing both nitrogen and phosphorus, is also 
widely distributed in animal tissue. 

Carbohydrates. The important carbohydrate of the animal 
body is glycogen, found in considerable quantities in the liver 
and in smaller amounts in the muscular tissue. It resembles 
starch in its constitution. At no time does it constitute an ap- 
preciable proportion of the animal's weight. In this respect 
animals differ from plants. In the latter the stored reserve ma- 
terial is usualty starch, while in the animal, fat is the reserve 
material. The glj^'cogen foimd in animal tissue has had its origin 
from the various carbohydrates of the feed. These have been 
absorbed from the digestive tract largely in the form of dextrose, 
one of the simpler sugars, and from which glycogen has been 
rebuilt. 

Composition of farm animals. The amounts of Avater, nitro- 
genous matter, fat .and ash constituents present in a large num- 



The Aninial Body. 



209 



ber of animals, have been determined by Lawes and Gilbert at 
the Rothamsted Station. The following table shows the per- 
centage composition of the whole bodies of various farm animals. 
The fat pig was one grown for fresh pork, not for bacon. Store 
animals are those in good flesh, but not fat. 



Composition of Farm Animals. 



Animal 



Water 



Fat 



Protein 


Ash 


Per cent 


Per cent 


15.2 


3.8 


16.6 


4.6 


14.5 


3.9 


12.3 


2.9 


14.8 


3.2 


14.0 


32 


12.2 


2.8 


13.7 


2.7 


10.9 


1.6 



Content of 

stomach, 

etc. 



Fat calf 

Half fat ox. . . 

Fat ox 

Fat lamb 

Store sheep. . 
Half fat sheep 
Fat sheep .... 

Store pig 

Fat pig 



Per cent 
63.0 
51.5 
45.5 

47.8 
57.3 
50.2 
43.4 
55.1 
41.3 



Per cent 
14.8 



19. 

30. 

28. 

18. 

23. 

35.6 

23.3 

42.2 



Per cent 
3.2 
8.2 
6.0 
8.5 
6.0 
9.1 
6.0 
5.2 
4.0 



It will be noticed that in nearly every case water is the largest 
ingredient of the animal body. The proportion of water is great- 
est in young and lean animals and diminishes toward maturity 
and especially during fattening. The proportion of nitrogenous 
matter and ash tends to increase as the animal ages, but dimin- 
ishes during fattening. The half fat ox contains 6 per cent more 
water than the fat; the store sheep 14 per cent more than the 
extra fat, and the store pig 14 per cent more than the fat. The 
fattening process does not involve a replacement of the water 
already in the tissues, but the increase is much more largely dry 
matter. Because this increase during fattening is largely fat, 
the proportion of protein and ash in the. dry substance of the 
fattened animal has decreased relatively. 

The largest proportion of nitrogenous matter and ash are 
found in the ox, the smallest in the pig. The difference in the 
proportion of ash is chiefly due to the wide difference in the 



210 



Agricultural Chemistry. 



proportion of bone in these two animals. Fat is found in great- 
est quantity in the pig and is least in the ox. 

The following table shows the quantity of nitrogen and the 
principal ash constituents in the fasted live weight of the animals 
analyzed at Rothamsted. The table is based upon a weight of 
1000 pounds for each animal. The table also includes milk, wool 
and eggs, and supplies information as to the loss a farm would 
sustain by the sale of animal products. According to this table, 
the ox contains, in proportion to its weight, a larger amount of 
nitrogen and a much larger amount of lime and phosphoric acid 
than either the sheep or pig. Of all the animals raised on the 
farm, the pig contains the least of all the important ash con- 
stituents. 

Attention should be called to the large amount of potash in 
unwashed wool. It is possible for the fleece to contain more 
potash than the whole body of the shorn sheep. The fleeces of 
four Hampshire Down sheep, analj'^zed at Rothamsted, contained 
about 6.5 per cent of nitrogen and 2 to 3 per cent of ash. 



Ash Constituents and Nitrogen in 1000 Pounds of Various Aiiimals and 
the Same Weight of Their Products. 



Animal 


Nitrogen 


Phos- 
phoric 
acid 


Potash 


Lime 


Magnesia 


Fat calf 


Lbs. 
24.6 
27.4 
23.2 
19.7 
23.7 
19.7 
22.0 
17.6 
54 
94.4 
5.7 
20.0 


Lbs. 

15.3 

IS. 3 

15.5 

11.2 

11.8 

10.4 

10.6 

6.5 

0.7 

1.8 

2.0 

4.2 


Lbs. t Lbs. 
2.0 ! 16 4 
2.0 21 1 
1.7 17.9 

1.6 i 12.8 

1.7 13.2 
1.5 11.8 
1.9 1 10.8 
1.4 I 6.3 

56.2 i 1.8 
1.9 ! 2.4 
1.7 ' 1-7 


Lbs. 

0.8 


Half lat ox 


0.8 


Fat ox 

Fat lamb 


0.6 
0.5 


Store sheep 

Fat sheep 

Store pig 


0.5 
0.5 
0.5 


Fat pip 

Wool (unwashed). . 

Wool (wa.shed) 

Milk 


0.3 
0.4 
0.6 
0.2 


Hen's eggs 


1.7 


60.8 


1.0 



The Animal Body. 



211 



Fattening an animal increases the proportion of butcher's 
meat while at the same time it materially modifies its composition. 
Jordan gives the proportion of dressed carcass in per cent as 
follows : 

Ox Sheep Swine 

Lean animal 47 45 73 

Fat animal 60 53 82 

The composition of the increase of an animal varies much un- 
der different circumstances. The increase of a young growing 
animal will contain much w^ater, protein and ash ; that of a ma- 
ture fattening animal will consist chiefly of fat. From this it 
follows that a larger proportion of protein and ash is needed 
during the earlier periods of growth ; but, because of the larger 
proportion of water, a smaller amount of food is required to 
produce one pound of gain. 

The composition of the increase of oxen, sheep and pigs, when 
passing from the "store" to the "fat" condition has been cal- 
culated by Lawes and Gilbert. 



Percentage Composition of the Increase 


While Fattening. 




Water 


Protein 


Fat 


Ash 


Sheep 


Per cent 
22.0 
24.6 

28.6 

25.1 


Per cent 

7 2 

7.7 
7.8 

7.6 


Per cent 

68.8 
66.2 
63.1 

66.0 


Per cent 
2.0 


Oxen 


1.5 


Pigs 


0.5 


Average 


1.3 







The increase during the fattening stage of growth is seen to 
contain 8 to 9 parts of fat for one of nitrogenous matter. 

Important parts of the animal body. Blood consists of a 
colorless liquid — plasma — holding in suspension numerous small 
solid bodies, the red and white corpuscles. The red corpuscles 
give the blood its characteristic color. These corpuscles have a 
definite structure and make up 30 to 40 per cent of the blood. 



212 Agricultural Chemistry. 

"When taken from an animal the plasma quickly deposits one of 
its protein constituents, fibrin, which, entangling the corpiLscles, 
causes them to separate as a clot from the yellowish liquid — the 
serum. Blood plasma is therefore the liquid portion of fresh 
blood, while blood serum is the liquid portion after clotting. The 
latter differs from the former by having lost its fibrin and a 
portion of its lime, magnesia and phosphoric acid. 

Blood is the nutrient fluid of the body. It is the source of 
nourishment for all the cells. Out of its ingredients the tissues 
are built. It contains about 81 per cent of water, so that it 
easily holds in solution whatever soluble nutrients are furnished 
it from the digestive tract. 

The 19 per cent of solids consists of the following materials: 
10 per cent of haemoglobm ; 7 per cent of proteins ; about 1 per 
cent of ash; the remaining 1 per cent consists of fats, sugars, 
lecithin, etc. The color of the blood is due to haemoglobin. This 
body is extremely complex in composition and contains about 
0.4 per cent of iron. Haemoglobin is a dark purplish-red colored 
substance. It readily combines with oxygen to an oxy-compound 
which is bright red in color. The haemoglobin plays an import- 
ant part in respiration as the carrier of oxygen to the tissues. 

The red corpuscles consist of circular, bi-concave discs, though 
their shape and size vary in different animals. They are largest 
in reptiles. In man the average diameter of a blood corpusle is 
about 1/3200 of an inch, and its thickness about 1/12800 of an 
inch. These corpuscles contain the haemoglobin, the coloring 
matter of the blood. When they are treated with water or ether 
they loose their coloring matter and leave a nitrogenous residue 
which retains the shape of the original corpuscles. 

Bones consist of an earthy frame work composed mainly of 
calcium phosphate, permeated by an albuminoid, called ossein, 
and by nerves, blood vessels, etc. In the hollow center of many 
bones is the marrow, which consists of fats and proteins. The 
relative proportion of mineral and organic matter in bones varies 
considerably. The amount of mineral matter in the green bone 



The Animal Body. 213 

varies from 40 to 60 per cent. No definite percentage can be 
given, as the amount, up to a certain limit, will vary with the 
supply of lime and phosphoric acid in the food and also with 
the source of the bone. 

The ash of bone is not entirely phosphate of lime, but contains 
in addition carbonates, fluorides, chlorides and magnesia. The 
following analysis of bone ash is given by Ingle : 

Calcium phosphate 86.0 per cent 

Magnesium phosphate 1.0 

Calcium, as carbonate, chloride and fluoride. . . 7.3 

Carbon dioxide 6.2 

Chlorine 0.2 

Fluorine 0.3 

Muscular tissue consists largely of proteins and water, but 
contains in addition small quantities of fat, glycogen (animal 
starch), and certain nitrogenous extractives, such as creatin, 
creatinin, xanthin and guanin. Small quantities of dextrose are 
also contained in muscle tissue. The ash of muscle consists 
largely of potash and phosphoric acid compounds, but there are 
also present small amounts of sodium, magnesium, calcium, chlo- 
rine and iron. Muscle usually contains about 75 to 80 per cent 
of water, and 20 to 25 per cent of solids. 

"When a muscle does work, the glycogen and sugar are burned 
at an increased rate and the blood, which bathes the muscle, re- 
ceives an increased proportion of carbon dioxide. Fats are also 
sources of mechanical work for the muscle. "When fats and 
carbohydrates are available for consumption, the nitrogenous 
waste of the muscle is not increased by exercise, and only the 
normal amount of waste nitrogenous products, as urea, uric acid, 
etc., appear as the result of the life processes. 

Fatty tissue is made up of relatively large, oval, or spherical 
cells. These cells consist of a nitrogenous membrane, filled with 
fat, which during life is fluid. The fats, which resemble in con- 
stitution the vegetable oils already described, are chiefly com- 
posed of stearin, palmitin and olein. The fat cells may be 



214 Agricultural Chemistry. 

found deposited between the fibers or cells of muscular tissue, 
or may constitute almost the entire mass of adipose tissue. 
"When the latter is the case, the fatty tissues will consist of water, 
membrane and fat in about the following proportions: — 

Ox Sheep Pig 

Water (percent) 9.96 10.48 0.44 

Membrane " 1.16 1.64 1.35 

Fat " 88.88 87.88 •»2.21 

Fat is stored in the body as a reserve material from w^hich the 
animal can draw in time of scarcity of food. It is the most con- 
centrated form in which energy is stored in the animal. 

Connective tissue, of which tendons, ligaments, cartilage and 
skin are mainly composed, consists of substances which yield 
gelatine when heated with water. These are the albuminoid com- 
pounds and constitute the framework of the animal tissues. They 
are to the animal body what cellulose is to the vegetable kingdom. 
They are only slightly attacked by acids and alkalies and are 
insoluble in water and salt solutions. Several different bodies 
have been recognized, among which are elastin, collagen and 
keratin. The first is the principal constituent of the elastic tis- 
sues and contains but traces of sulphur. The second, collagen, 
constitutes the foundation of cartilage and may be extracted from 
these tissues with hot water. The product which goes into solu- 
tion is called gelatine and solidifies on cooling. It contains about 
0.6 per cent of sulphur. The third substance, keratin, is the main 
constituent of hair, horn, hoof, feathers and wool, and contains 
4 to 5 per cent of sulphur. It is insoluble in water, but by heat- 
ing with Avater mider pressure to 150-200° C. it may be rendered 
soluble and then constitutes glue. 

Processes of nutrition. We have seen that the food of plants 
is of the simplest character and from such simple materials as 
carbon dioxide, nitrates, certain other inorganic salts and water. 
a plant is able to construct a great variety of complex compounds. 
It accomplishes these surprising transformations by a consump- 
tion of energy (sunlight) external to itself. An animal has no 



The Animal Body. ■ 215 

such power. The animal tissues are built up from the complex 
substances existing ready-formed in the food. The animal de- 
rives no aid from external energy. The temperature of the 
animal body (about 100° F.) is maintained by heat generated 
within the body and by the combustion of the material consumed 
as food. The energy by which all the mechanical work of the 
animal is performed, comes from the same source. The source 
of heat and force in the animal is thus purely internal. 

It is apparent from what has been said that the food of animals 
has duties to perform which are not demanded of the food of 
plants. In plants the food chiefly provides material for build- 
ing up the vegetable tissues. In the animal, besides constructing 
tissue, the food must furnish the means of producing heat and 
performing mechanical work; to accomplish this result, it must 
be burned in the animal body. 

Functions of food constituents. The solid ingredients of 
vegetable food may be classed, as (1) proteins; (2) fats; (3) car- 
bohydrates; (4) salts. Besides these general classes of food 
constituents, we have in immature vegetable products, as hays, 
roots, etc., a fifth class — the amino-acids and amides — which also 
take part in animal nutrition. They are the simple intermed- 
iary nitrogenous substances, formed from the nitrates absorbed 
by the plant, and eventually take part in the construction of 
the complex proteins of seeds and plant tissue. 

The proteins occurring in seeds, roots and other forms of 
vegetable food, have a general similarity in composition to those 
found in milk, blood, and flesh, but are by no means identical. 
From the proteins of the food are formed not only the proteins 
of the soft tissues of the animal, but also such a class of proteins 
as the albuminoids, which differ so materially in properties from 
the proteins of blood and muscle. It is also very probable that 
fat, a non-nitrogenous body, may be formed from protein. This 
is still a much disputed question and it remains for future in- 
vestigations to definitely decide this point. 

Proteins can also serve as a source of energy. In the case of 



216 Agricultural Chemistry. 



% 



a dog eating exclusivelj'" a meat diet, probably a greater part of 
the protein eaten is not stored but is used as fuel. We see from 
this that the proteins can serve most of the requirements of the 
animal, a statement which cannot be made of any other food 
constituent. They are the true tissue builders. 

An animal, even when not increasing in weight, will always 
require a certain constant supply of protein in its food to replace 
the waste of nitrogenous tissue, which is always going on even 
during rest. The cell proteins are constantl}^ undergoing de- 
composition and reconstruction. 

"When the nitrogenous tissues of the animal, or the proteins 
consumed as food are decomposed in the body, the nitrogen they 
contain is largely excreted in the form of a simple nitrogenous 
substance, urea. This is eliminated hj way of the kidneys in the 
urine. There are small quantities of other nitrogenous products, 
such as uric acid, creatin, creatinin, and in the case of herbivora, 
hippuric acid, voided in the urine, but they constitute but a 
small proportion of the total nitrogen eliminated. The urea pro- 
duced is rich in nitrogen, containing about 46.6 per cent. It 
represents about one-third the weight of the protein oxidized. 

The amides and amino-acids consumed as food are burned in 
the body and their nitrogen excreted as urea. It is very prob- 
able that they can, in part, take the place of proteins as tissue 
builders. In addition, by their combustion, they serve as sources 
of heat and force. 

The fats are free from nitrogen. Those contained in food are 
similar to those found in the animal body. It appears possible 
for a vegetable fat to become deposited in the animal without 
essential change. Small deposits occur in every organ and cell. 
The fat resers'^es vary much in size, depending on nutritive con- 
ditions, so that no definite statement can be made regarding the 
fat content of the individual organs. The fat of the food is 
either burned in the animal system to furnish heat and mechan- 
ical energy or is stored up as reserve material. With their larger 
content of carbon and smaller proportion of oxygen, fats are less 



The Animal Body. 217 

easily oxidized than sugars and require a larger intake of oxygen 
for their combustion; but when oxidized they yield more heat 
per pound than any other food ingredient. 

The carbohydrates of the food are chiefly starch, sugai-s, cel- 
luloses and pentosans. Various other non-nitrogenous constit- 
uents of food, such as the pectins, lignin and vegetable acids, 
are generallj'' included under this title, though they are not, 
strictly speaking, carbohydrates. Carbohydrates form the larg- 
est part of all vegetable food. They are not permanently stored 
in the animal body, but serve when burned in the system, for 
the production of heat and mechanical work. If a fattening 
steer were consuming 16 pounds of digestible organic matter and 
gaining two pounds of live weight daily, the body increase and 
urine would contain not over 2.5 pounds of dry matter, leaving 
not less than 13.5 pounds to be oxidized, of which 12 pounds 
might consist of carbohydrates and fat, mostly the former. 

The carbohydrates are also capable, when consumed in excess 
of immediate requirements, of conversion into fat. The well- 
recognized value of corn meal as a fattening food, a feeding stuff 
nearly seven-tenths of which consists of starch and similar struc- 
tures, is a practical illustration of this truth. 

The carbohydrates and fats are the natural fuel food stuffs of 
the body. They cannot serve for the renewal or upbuilding of 
tissue, but by oxidation they constitute an economical fuel for 
maintaining body temperature and for power to run the bodily 
machinery. Proteins may likewise serve as fuel, but this is ap- 
parently confined to a non-nitrogenous part of their molecule. 
When fats or carbohydrates are available the proteins of the tis- 
sue are not normally consumed for production of heat and force. 
Only when the former are lacking will the animal increase its 
protein metabolism and nitrogen output for purposes of main- 
taining the body temperature. A moderate quantity of protein 
supplied to a growing animal will thus produce a much larger 
increase of muscle when accompanied by a liberal supply of car- 
bohydrates or fats. In this case, the non-nitrogenous constit- 



218 Agricultural Ohemistry. 



1 



uents of the food supply the demands for heat and work and 
the protein can be devoted to the rebuilding or increase of tissue. 

If an adult animal receives the small amount of protein and 
salts necessary to repair the daily waste of tissue, it would be 
expected that the whole of the remaining wants might be met by 
supplying carbohydrates or fats. This is to some extent true; 
but a ration very poor in protein is not found to be consistent 
with real bodily vigor. There is some specific action of i)roteins 
not as yet understood. They. appear to stimulate cell activity, 
a property not possessed by fats and carbohydrates. 

The ash constituents present in food are the same as those 
found in the animal body. The animal simply selects from the 
digested ash constituents those of which it is in need. The tissue, 
the blood, digestive fluids, and the bony framework contain a 
variety of these bodies, which are as essential as any of the other 
substances considered for the building and maintenance of the 
animal body. Without lime and phosphoric acid there can be 
no bone formation, and the digestive juices would cease to be 
active if deprived of chlorine. A cow from which common salt 
is withheld will, in time, die. Not only must the growing calf 
have ash material for constructive purposes, but the mature ox 
must be supplied with them in order to sustain the nutritive 
processes. The milch cow, which stores combinations of lime, 
phosphoric acid, potash and other salts in the milk, must have 
an adequate supply of these materials. Nothing else can take 
their place. Lime and phosphoric acid, stored in abundance in 
the framework of the animal, maj'' at times of deficient supply 
in the food, act as internal sources; but ultimately all ash ele- 
ments must have been contained in the food. 

Digestion. We have accepted so far AAathout discussion the 
self-evident fact that the food is the immediate source of the 
energy and substance of the animal body. It is now necessary to 
consider the way in which the nutrition of the animal is accom- 
plished. Digestion is the important process by which the food 
of an animal is rendered capable of being absorbed into the sys- 



The Animal Body. 219 

tem and utilized in building up or renewing the tissue of the 
body. Hay and grain cannot directly be transferred to the 
blood, but must first be brought into soluble and diffusible con- 
dition before they can pass out of the alimentary tract into the 
blood and lymph. This is accomplished partly by mechanical 
means, but mainly by chemical changes, which are produced 
chiefly by the action of bodies called enzymes. 

Enzymes are a peculiar class of substances produced by living 
cells which constitute the various secreting glands. They are of 
unknown composition and are peculiar in that the chemical 
changes which they induce are the result of what is called cat- 
alysis, or contact. That is, during the solution of the food stuffs, 
the enzyme is not used up or destroyed, but by its mere presence 
sets in motion or quickens a reaction between two other sub- 
stances. For example, the enzyme of the saliva causes the starch 
of the food to combine with water, with the result that the soluble 
sugar maltose, is formed. An enzyme that acts upon starch, for 
example, cannot act on proteins or fats. Some digestive fluids 
have the power of producing changes in different classes of food 
stuffs, but when this occurs, it is assumed to be due to the presence 
in the same fluid of different enzymes. Again, enzymes are sen- 
sitive to their environment, and a proper temperature and re- 
action must be maintained for their activity. The activity of 
saliva is extremely sensitive to the nature of the reaction and 
ceases when that becomes acid. Enzymes are thus seen to be 
more or less unstable substances, endowed with great power as 
digestive agents, but sensitive to a high degree and working ad- 
vantageously only under definite conditions. 

Digestion in the mouth. The first step is mastication, by 
which the food is subdivided and crushed by the action of the 
teeth and thoroughly mixed with saliva. This special secretion 
has its origin in several secreting glands, and from these this 
liquid is poured into the mouth through ducts, opening in the 
cheek under the tongue. Saliva is a highly dilute liquid of faint- 
ly alkaline reaction and contains an enzyme, ptyalin, which has 



220 Agriculhiral Chemistry. 



3 



the power of bringing about the same changes as are produced 
by plant diastase, that is, the conversion of starch into the sugar, 
maltose. This change begins in the mouth and continues for a 
limited time in the stomach, or until the gastric secretions es- 
tablish an acid reaction in the stomach contents. When this is 
established, salivary digestion ceases. The proteins and fats are 
not attacked by the salivary secretion. 

Ruminants, whose feed usually contains much starchy material, 
secrete enormous quantities of saliva. It is estimated that oxen 
and horses secrete from 88 to 122 pounds daily. This serves the 
additional important function of properly preparing the food 
for swallowing. 

Gastric digestion. The food after mastication passes down 
the gullet into the stomach. In the case of the horse and pig the 
stomach is a single sac, and true gastric digestion begins at once. 
In ruminants, as the ox and sheep, the stomach consists of four 
divisions, or sacs, and not until the fourth is reached, does gastric 
digestion proper begin. These sacs may be considered as en- 
largements of the oesophagus and primarily for the storage of 
the buUjy materials consumed by these classes of farm animals. 
The four divisions are the paunch, honey-comb, many-plies and 
rennet, or what the anatomist has called the rumen, reticulum, 
omasum and abomasum. The capacity of these cavities in the 
ox is, on the average, not far from 50 to 60 gallons, about nine- 
tenths of the space belonging to the paunch. It is in the paunch 
that the food is first stored, only the finer portions being carried 
by what is known as the oesophagal groove to the third stomach, 
and finally from this compartment into the fourth and last di- 
vision. From the paunch the food is returned to the mouth 
where it is more finely ground before passing to the fourth stom- 
ach for digestion. This is what is termed "chewing the cud." 
In the paunch salivary digestion probably continues, as well as 
other fermentations induced by various micro-organisms. Here 
possibly a partial fermentation of cellulose by bacterial enzymes 
begins. 



The Animal Body. 



221 



When the food reaches the fourth stomach, it meets with the 
characteristic secretion of that organ, the gastric juice. This 
juice is secreted by glands located in the mucus membrane of 
the stomach. It is a watery fluid, containing various salts, as 
chlorides and phosphates of calcium, magnesium, sodium and 
potassium, free hydrochloric acid and the two enzymes, pepsin 
and rennin. The combination of pepsin and the acid is the ef- 





On the left — stomach of the horse. A, end of the oesophagus; B, pyloric 
end, or beginning of the intestine. On the right— stomach of the 
sheep. O, oesophagus; P, rumen; R, reticulum; P, omasum; 
C, abomasum; I, commencement of the small intestine; 1, oesophagal 
groove; 2, opening between omasum and abomasum. 

fective agent in the digestion. They are secreted by different 
gland cells in the stomach walls and the amount of hydrochloric 
acid secreted during 24 hours by a normal man, under ordinary 
conditions of diet, amounts to what would constitute a fatal dose 
of acid, if taken at one time in concentrated form. The main 
action of gastric juice is exerted on the proteins of the food, 
which under its influence, are gradually dissolved and converted 
into soluble products, known as proteoses and peptones. This^ 
enzyme, like the ptyalin of the saliva, is influenced by tern- 



222 Agricultural Chemistry. 

perature, maximum digestive action being manifested at about 
38° C, the temperature of the body. Further, a certain degree 
of acidity is essential for procuring the highest degree of effi- 
ciency. Pepsin acts best in the presence of from 0.1 to 0.3 per 
cent of free hydrochloric acid. It is said that the gastric juice 
of the sheep has a low acidity, while that of the dog has the high- 
est recorded among mammals. 

Chemically, the results are the same in the stomachs of all farm 
animals, that is, the proteins are changed to the soluble fonns 
known as proteoses and peptones. The utilization of coarse fod- 
der by the horse is not as complete as in the ox for the reason 
that in the case of the former there is no preliminary remastica- 
tion and trituration before the food material comes in contact 
with the gastric juice. 

Another important function of gastric juice is that of curdling 
milk, due to the presence in the secretion of the peculiar enzyme 
known as rennin. This is present in the stomach of all mammals 
and it is the calf's active secretion, which is the source of com- 
mercial rennet used in cheese making. The purpose of this 
enzyme can only be conjectured. As the sole nutriment of the 
young, milk occupies a peculiar position as a food stuff, and be- 
ing a liquid, its protein constituents might easily escape complete 
digestion were it to pass too hastily through the digestive tract. 
Experiments have shown this to be true of liquid foods. But 
when curdled by the rennin, the proteins of the milk in their 
clotted state, must remain for a longer time in the stomach, and 
their partial digestion by gastric juice made certain. 

Among other factors in gastric digestion, the muscular move- 
ments of the stomach walls are to be emphasized, since we have 
here a mechanical aid to digestion of no small moment and like- 
wise a means of accomplishing the onward movement of the 
stomach contents. From the stomach but little absorption of the 
soluble food materials takes place. It is in the intestine that both 
digestion and absorption are at their best. 



The A7iimal Body. 223 

Digestion in the intestine. "When the food leaves the stomach 
it enters the small intestine. At this point it is only partially 
digested. The fats of the food have not as yet been changed, 
and undoubtedly a considerable proportion of the proteins and 
carbohydrates susceptible to solution is still to be acted upon. 
Immediately after passing from the stomach, the partially di- 
gested mass comes in contact with the pancreatic juice, the bile 
and intestinal juice, and the changes which began in the mouth 
and stomach, together with others which set in for the first time, 
proceed at a vigorous rate. The bile is secreted by the liver and 
stored in the small sac attached to that organ and called the 
' ' gall bladder ' ' and from which it is brought to the intestine by 
a duct opening near the orifice leading out of the stomach. Bile 
is a reddish-yellow (in carnivorous animals) or green (in herb- 
ivora) liquid, with an alkaline reaction and bitter taste. It con- 
tains complex salts, which in conjunction with the fat splitting 
enzyme of the pancreatic juice, reduces the fats to an emulsion, 
a form in which they can be absorbed into the blood. "When bile 
is prevented from entry into the intestine, the fat of the food 
largely passes out in the feces. Besides this important relation 
to fat digestion, the bile also acts in some degree as an anti- 
septic, preventing putrefaction in this part of the intestine. 

The pancreatic juice is of strongly alkaline reaction due to its 
content of sodium carbonate, and is characterized by the pres- 
ence of at least three distinct enzymes ; these are trypsin, a pro- 
tein digesting ferment ; lipase, a fat splitting enzyme ; and amy- 
lopsin, a starch digesting enzyme. This juice comes from the 
pancreas and enters the intestine through a small duct, which 
in some animals is confluent with the bile duct. By the action of 
this juice, the acid chyme from the stomach is rapidly converted 
into an alkaline mass and the enzyme pepsin is quickly destroyed 
in the new environment. Trypsin, effective in alkaline media, 
now continues the protein digestion, splitting the proteoses and 
peptones, as well as unattacked proteins, into simpler structures. 
In this act it is aided by another enzyme, known as erepsin, 



224 Agricultural Chemistry. 



I 



secreted by the mucus membrane of the intestine. These two 
enzymes are powerful agents and under their combined action 
the proteins are reduced, in part at least, to simple fragments, 
the amino-acids. 

The fatty foods undergo little or no alteration until they reach 
the intestine. While in the stomach they become liquid from 
the heat of the body and the neutral fat is liberated from the 
cell structures by the action of the gastric juice. Most of the 
neutral fats must be decomposed into the fatty acids and gly- 
cerine, of which they are composed, before absorption into the 
blood can take place. Under the influence of the fat splitting 
enzyme of the panereative juice, lipase, and the bile salts, the 
neutral fats are partly decomposed, with formation of soaps. 
These soaps aid in the formation of an emulsion of the rest of 
the fats. Such an emulsion is reallj'^ a suspension of the fat in 
a very finely divided condition. Soap, free acid and glycerine 
are then absorbed from the intestine and are found again com- 
bined in the lymph as neutral fat. In this way the fats are ren- 
dered available for the nourishment of the body. 

The transformation of starch into maltose is again taken up 
by the amylopsin of the pancreatic juice. The maltose is further 
exposed to an enzyme of the intestinal juice, termed rualtase, 
and decomposed into the simple sugar, dextrose. Other carbo- 
hydrates, as the lactose of milk, and cane sugar, meet \\\t\\ special 
enzymes in the intestinal juice, capable of converting them into 
simple sugars, the final fonn in which the carbohydrates are 
absorbed. 

No special enzymes fermenting the celluloses and pentosans, 
which constitute a large proportion of hays and straws, have as 
yet been prepared from the normal secretions of the intestinal 
tract. Possibly their partial solution is effected by bacterial fer- 
ments and other low forms of life. Such solution may have its 
beginning in the paunch, where active fermentations are in 
progress, and continue in the lower portions of the digestive tract. 



The /hiimal Body. 225 

Absorption of food. In the ways mentioned above, the pro- 
teins, fats and carbohydrates of the food are gradually digested. 
Throughout the length of the small intestine absorption proceeds 
rapidly; water, salts and the products of digestion pass out 
from the intestine into the circulating lymph and blood. There 
are two pathways by which absorbed material reaches the blood. 
In the intestinal wall are numerous projections, called villi. Im- 
bedded in these structures are the minute branches of two sys- 
tems of vessels. One set is the lacteals, belonging to the lym- 
phatic system and the other the capillaries of the blood system. 
Materials passing into the lacteals reach the thoracic duct and by 
it, in a roundabout way, are carried into one of the main blood- 
vessels at the neck. As a general truth it may be stated that the 
fats are largely absorbed through this channel, and it is impor- 
tant to observe that when they reach the lacteals they are again 
in the form of neutral fats. 

Materials absorbed by the capillaries of the blood system are 
carried directly to the liver through the portal vein, and there 
subjected to the action of that organ before they enter the gen- 
eral circulation. Most salts and the carbohydrates and proteins 
follow this course. In the liver the soluble sugars are converted 
into glycogen, the animal starch, and as such temporarily stored. 
The amount of sugar in the blood is a constant but small quan- 
tity and as this is required in the tissue, the glycogen is recon- 
verted back into soluble sugar to maintain the supply in the 
blood. 

The fragments of protein digestion, the proteoses, peptones 
and amino-acids, are not found as such in the blood or at least 
only in traces. Either in passing through the intestinal wall, 
or after reaching the liver, they are reconstructed into complex 
proteins before being cast loose into the circulatory system. 
These reconstructed proteins are the serum albumin, serum glo- 
bulin and haemoglobin of the blood, which serve as sources of 
protein for the various body tissues. The processes of absorption 



226 Agriculhind Chemistrij. 

and blood regulation are wonderfully and delicately balanced and 
are by no means completely understood. 

Feces. The portion of the food which has escaped solution 
and absorption, together with certain substances already absorbed 
but re-excreted by way of the intestines, constitute the feces. 
Epithelial cells from the intestinal walls, parts of the digestive 
juices, bile, bacterial cells, etc., will make up a large portion of 
the fecal matter. 

Respiration. The nutrients, prepared by the various process- 
es of solution and reconstruction in the intestines and intestinal 
wall, enter the blood on its return to the heart, coming into the 
venous circulation by way of the thoracic duct and liver (hep- 
atic vein), as already described. By this route, the blood, laden 
with nutrients, passes to the right side of the heart. It is then 
carried to the lungs, by way of the right ventricle, to be returned 
to the left side of the heart, and from which it is pumped to all 
parts of the body. In the lungs the blood is supplied with oxy- 
gen. The purple of venous blood is changed to a scarlet, due 
to the absorption of oxygen by the haemoglobin, with the forma- 
tion of oxy-haemoglobin, the important oxygen carrier of the 
blood. At the same time, a considerable quantity of carbon 
dioxide, most of which was in solution in the blood plasma, pos- 
sibly as a bi-carbonate, is given up to the air A^nthin the lungs. 

Inspired air contains about 21.0 per cent of oxygen and .03 
per cent of carbon-dioxide, while expired air carries approx- 
imately 16.5 per cent of oxygen and 4.4 per cent of carbon-diox- 
ide. Though the absorption of oxygen takes place in the lungs, 
it is not there that the processes of combining the oxygen with 
the carbon and hydrogen of the body tissues takes place. The 
blood, through the haemoglobin of the red-blood corpuscles, acts 
as a carrier of oxygen and the actual combustion of the products 
derived from the food occurs in the tissues themselves. The rate 
of combustion in the tissues is a variable one, dependent upon 
the amount of work the animal is doing and the temperature to 



The Animal Body. 22 Y 

which it is exposed. And it is through this oxidation of the 
nutrients in the cells of the body that heat and mechanical work 
are produced. 

Elimination. As has already been noted, the undigested resi- 
dues of food, together with certain excretory products eliminated 
by way of the intestines, constitute the feces. 

The products, which result from the metabolism of the body 
cells, or of the food consumed, are removed from the body by the 
lungs, the kidneys, the skin and the intestine. The carbohyd- 
rates and fats, which are oxidized in keeping up the animal heat 
or in furnishing energy, are broken down into carbon-dioxide 
and water and removed as such from the blood in the lungs, and 
to a smaller extent by the skin. Water and salts are removed by 
both intestine and Iddney, while the perspiration may also serve 
to carry considerable quantities of these materials. The elimina- 
tion of the products of protein degradation in the tissues is al- 
most entirely by way of the kidneys. The larger part of the 
nitrogen is eliminated in the form of the simple body, urea. There 
are other forms of nitrogen occurring in the urine, such as uric 
acid, creatin, creatinin, ammonia, etc., but they constitute only a 
small proportion of the total nitrogen eliminated. 

The sulphur of the protein molecule is also removed as sulphate 
through the kidney, while the phosphorus passes out of the body 
in the form of a phosphate by both the intestines and kidney; 
by far the larger proportion is removed through the intestine in 
the herbivora. 

The quantity of nitrogen in the urine is taken as a measure of 
the amount of protein decomposition in the tissue. This may be 
only partly true. It is now believed that a considerable part of 
the nitrogen of ingested protein has not been built into body 
tissue, but is eliminated from the protein molecule as ammonia 
in the intestine, carried to the liver, and from there finally ex- 
creted through the kidney as urea. The carbonaceous part of 
the protein molecule from which this nitrogen has been removed 



228 Agricultural Chemistry. 

may now be used, through combustion, as a source of energy for 
the animal body. 

"When an animal is supplied with known quantities of food per 
day, it is possible, by collecting the feces and subjecting it to the 
same chemical analysis as was applied to the food, to determine 
how much of each constituent of the food has been digested by 
the animal. This applies particularly to carbohydrates, fats and 
proteins, although not strictly accurate for these. It does not 
apply to the mineral salts, as they are partly excreted through 
the intestine. But by such means the digestibility of feeds is 
measured and such results are of enormous value to the knowledge 
of animal feeding. 



CHAPTER X 
FEEDING STANDARDS 

We have traced in the preceding chapter the processes of solu- 
tion and the destination of the various nutrients of feeding ma- 
terials. It will now be necessary to consider briefly the develop- 
ment of our knowledge leading to the establishment of feeding 
standards and the present status of such information. In 1810 
Thaer, in Germany, formulated the first standard, publishing a 
table of hay equivalents, using meadow hay as the standard. It 
had little experimental foundation and soon fell into disuse. In 
1859 Grouven published the first standard based upon the quan- 
tity of proximate constituents in feeding materials. 

The work of Liebig, Boussingault, and others, with the new 
tools of a rapidly developing chemistry, was paving the way for 
standards based on chemical analysis. But the tables of Grouven 
did not meet the requirements, since they were based on the total, 
instead of the digestible nutrients. 

In 1864 the feeding standards of Wolff, the eminent German 
scientist, first appeared. They are based upon the amounts of 
digestible protein, carbohydrates and fats, required by the va- 
rious classes of farm animals. These standards have been pub- 
lished annually in the Mentzel-Lengerke calendar down to 1896 ; 
for the next ten years they were issued by Lehmann of the Berlin 
Agricultural High School, and since 1907 by Kellner, modified 
to a starch equivalent basis, to be described later. The Wolff 
standards have seen wide use by practical stockmen because of 
their simplicity and definiteness. 

Co-efficient of digestibility. The nutrients of feeds are not 
wholly digestible. A part passes through the animal without 
having been dissolved by the digestive juices and thereby made 
available to the animal. The general method of measuring the 
digestibility of feeds has been to supply the animal with weierhed 



230 



Agricultural Chemistry. 



quantities of the feed, the composition of which has been de- 
termined by chemical analysis. During the experiment the solid 
excrement is collected and weighed and finally analyzed by the 
same methods as those previously applied to the feed. From the 
data thus collected the digestion co-efficients are calculated. 
Example : 



Digestion Experiment with Sheep {From Henry). 



Dry 
Matter 



Protein 





Nitro- 


Crude 


gen 


fiber 


free 




extract 



Ether 
extiact 



Fed 700 grams of hay (con- 
taining) 

Excreted 610.6 grams dung 
(containing) 

Digested 

Per cent digested 



Grains Grams 



586.1 

288.6 
297. r> 

50.8 



77.7 

40 4 
37.3 
48.0 



Grams 


Gram^ 


191.7 


27() 7 


101.5 
90.0 
47.1 


119.4 

157.3 

56.8 



Grams 

10.7 

7.9 

2.8 

26.2 



From the example it will be seen that the digestion co-efficient 
is the proportion of each food constituent digested out of 100 
parts by weight supplied. The figures secured are not absolutely 
accurate, due to intestinal secretions which become reckoned as 
undigested food. The co-efficients for proteins and fats suffer 
most in this regard. In experiments with oat straw the fecal nit- 
rogen has been found to be more than that in the food, although 
the protein of the straw must have been digested to a considerable 
extent. Jordan states: "It is probably safe to affirm that at 
least 10 should be added to the co-efficients of digestibility of the 
protein of coarse fodders, as usually given in the tables that have 
been compiled." "With fat co-efficients, an error is introduced 
through the secretion of bile into the intestine. This material 
contains products soluble in ether, the usual reagent used in de- 
termining the fat content of the feeding stuff. Consequently the 
undigested fat appears larger than it really is. 



Feeding Standards. 231 

Conditions affecting digestibility. Animals differ in their 
power of digesting any given food or food constituent. For ex- 
ample, the ruminants, by their more thorough and repeated mas- 
tication, are better able to digest bulky fodder than are pigs and 
horses. This is illustrated in the following table taken from 
Jordan : — 

Dry Substance Digested from Meadow Hay [Per Cent). 

Samples Best Medium Poor 

Sheep 42 67 61 55 

Oxen 10 67 64 56 

Horses 18 58 50 46 

On the other hand the power of digesting bulky feeds by dif- 
ferent classes of ruminants is very similar. Steers have been 
compared with sheep, and cows with goats, with no uniform dif- 
ference in their digestive power for this class of feeds. 

With the grains, the differences in digestibility with the various 
classes of farm animals are not greatly imlike. Comparative 
trials of oats with sheep and the horse gave nearly identical di- 
gestibility of the dry matter. With cows the result was similar. 
In other trials where beans were used the advantage was slightly 
with the ruminant. Swine digest the concentrated feeds as com- 
pletely as do ruminants or the horse. Nor are they incapable of 
digesting vegetable fiber when presented in a favorable condi- 
tion. Pigs fed on green oats and vetch digested 48.9 per cent 
of the fiber supplied. However, the digestive apparatus of the 
pig is not adapted for dealing successfully with bulky fodder. 

So far as the influence of breed is concerned, this does not be- 
come a factor in the digestibility of feeds. A Jersey is as effi- 
cient in this capacity as a Holstein. Young animals appear to 
digest as efficiently as older ones of the same species. There are, 
very probably, differences in individuals, but the data so far 
collected do not definitely show this. 

The influence of quantity of food on digestion is an unsettled 
point. The old experiments of Wolff indicated that a full ration 
was as completely digested as a scanty one. More recent ex- 



232 Agricultural Chemistry. 



periments in Europe, as well as in this country, give opposite 
results, indicating a higher rate of digestibility with smaller 
rations. The difference is not large and with appetite regulating 
the consumption, it is fair to assume that variations in food in- 
take, incidental to normal feeding, will not markedly influence 
the power of digestion. 

Influence of the quality of feed on digestibility. It is a popu- 
lar belief that curing a fodder decreases its digestibility. This is 
probably true, especially where the drying has been conducted 
in a careless manner. The loss of leaves and the finer parts of 
the plant, and the washing out of soluble matter by rain are 
factors which will depress the digestibility of the fodder. For 
this reason, field cared corn fodder is considerably less digestible 
than silage coming from the same source. On the other hand, 
where the curing is done in such a manner as to exclude these 
losses, it is doubtful if it, in itself, has any appreciable effect 
upon digestibility. 

The stage of growth of a fodder plant vnW influence its di- 
gestibility. That stage where there is a relatively high propor- 
tion of starch and sugar and a minimum of cellulose and lignins, 
will show a higher digestibility. As the grasses mature, the fiber 
increases; on the other hand, the corn plant furnishes a rela- 
tively higher proportion of digestible nutrients when the ears 
are full grown than before the ears have formed. 

Influence of methods of preparation. Steaming, wetting and 
cooking the feed have received considerable attention. The gen- 
eral concensus of opinion of feeders, as well as the results of 
scientific experiments, do not indicate that these practices are 
of great advantage ; beans, corn and bran are not better digested 
by the horse or ox when previously soaked in water. Barley, 
corn and pea meal have been found more nourishing for pigs 
when given dry than when previously cooked. Cooking certainly 
depresses the digestibility of the proteins. This has been ex- 
perimentally demonstrated with steamed hays, silage, com meal 



I 



Feeding Standards. 233 

and wheat bran. However, when cooking or steaming the feed 
renders it more palatable, and secures a larger consumption of 
material which otherwise would be wasted, the influence on di- 
gestibility is of less importance. 

Grinding increases the digestibility of feeds. Mechanical divi- 
sion is an important factor in the rate and completeness of solu- 
tion of material in the digestive tract. A single experiment with 
corn, fed to the horse, showed about 7 per cent increased digesti- 
bility from grinding, and with wheat, in one trial the increase 
was 10 per cent. With ruminants, the danger from imperfect 
mastication is less than with horses and swine. "Whether it will 
pay to grind the grain will depend upon the cost of grinding 
and the loss of nutritive material from not grinding. 

Influence of one feed on the digestibility of another. It is 
generally stated that the addition of a considerable quantity of 
protein to a ration of hay and straw consumed by a ruminant, 
is completely digested, without affecting the digestibility of the 
original feed. Pigs have been fed potatoes to which variable 
quantities of meat flour were added. The proteins of the meat 
were completely digested, while the proportion of potatoes di- 
gested remained unchanged. 

It is also claimed that the addition of fat or oil to a basal 
ration of hay and straw was without influence on their digesti- 
bility. 

On the contrary, Dietrich and Koenig state that if a carbo- 
hydrate, as starch or sugar, is added to the extent of more than 
10 per cent of the dry substance of a basal ration, or if roots or 
potatoes, equivalent in dry matter to more than 15 per cent, are 
fed, a diminution of digestibility occurs. It is further stated 
that the depression of digestibility is reduced, when, accompany- 
ing the high starch intake, there is a corresponding increase in 
protein consumption. From these considerations, it is stated 
that highly nitrogenous feeds may be given with hay and straw 
without affecting their digestibility; but feeds rich in carbohyd- 



234 Agricultural Chemistry. 



I 



rates, as potatoes and mangels, cannot be given in greater pro- 
portion than 15 per cent of the fodder (both calculated as dr>^ 
food) ^^dthout diminishing the digestibility of the latter. 

Lindsey of the Massachusetts Station has, in part, confirmed 
the work of Dietrich and Koenig. He found that when Porto 
Rico molasses fed together with hay, constituted from 10 to 15 
per cent of the total dry matter of the ration, little if any de- 
pression occurred. But with molasses constituting 20 per cent 
of the dry matter of the ration, a depression of 4.5 per cent was 
noted in the digestibility of the hay. He concluded that molasses 
and hay would not make a satisfactoiy combination for farm 
stock. A more suitable ration would consist of hay, together 
with one or more protein concentrates and molasses. Even in a 
ration of hay and gluten feed and in which molasses composed 
20 per cent of the dry matter, there was a depression of 8 per 
cent in the digestibility of the hay and gluten. 

The nutritive ratio. We have seen that the formulation of 
feeding standards must be based on a knowledge of the relative 
digestibility of the several nutrients contained in the feeding 
material. Such knowledge has been secured by many experi- 
menters, working with various classes of farm animals, and has 
given us our tables of co-efficients of digestibility available in 
books on animal feeding. (See table in Appendix.) 

It has been found in practice that the feed of an animal may 
be varied within fairly wide limits, provided the ratio of digest- 
ible protein to all other digestible organic matter is kept within 
certain limits. Protein has special and peculiar functions and 
less than a certain minimum would limit production by just the 
amount of the deficiency. Jn order to get this ratio it is neces- 
sary that some carbohydrate be taken as a standard for express- 
ing the non-protein portion of the ration. Starch is the sub- 
stance always chosen, and it becomes necessary, in order to ex- 
press the fats and other carbohydrates in terms of starch, to ob- 
tain the equivalent in heat producing power of the other food 
constituents. This has been secured (1) by burning a weighed 



Feeding Standards. 235 

portion of the various materials in a calorimeter (an instrument 
for measuring heat production), and (2) by direct experiments 
upon animals placed in a respiration calorimeter (an apparatus 
for measuring both gas and heat production) , and fed with known 
weights of the various feeding-stuffs. As an average of several 
experiments it may be taken that one part of fat evolves as much 
heat as 2.4 parts of starch, sugar, cellulose or of protein. To 
express the non-protein, other than carbohydrates, in terms of 
starch, it is therefore necessary to multiply the quantity of di- 
gestible fat by 2.4 and add this product to the quantity of digest- 
ible carbohydrates present. The nutritive ratio thus becomes : 

digestible protein 
digestible carb. -f (dig. fat X 2.4) 

The nutritive ratio of corn meal is obtained as follows; 

100 lbs. contain 7-9 lbs. digestible protein 

66.7 lbs. digestible carbohydrates 
■1.3 lbs. digestible ether extract (fat) 

7.9 7.9 7.9 1 



66.7 + (4.3 X 2.4) 66.7 + 9.32 76.02 9.6 

The nutritive ratio for corn meal is therefore 1 :9.6. This 
means that for every pound of digestible protein in com meal 
there are 9.6 pounds of digestible carbohydrates and ether ex- 
tract (fat) equivalent. The term "wide" ratio is used when 
there is a very large proportion of carbohydrates contained in a 
feed in proportion to the protein. Oat straw, with a nutritive 
ratio of 1:33.7, is an example of a very ''wide" nutritive ratio. 
With corn the ratio is "medium," while with oil meal, with a 
ratio of 1:1.7 the expression "narrow" is used. 

The Wolff-Lehman feeding standards. In 1864 Wolff pro- 
posed certain feeding standards, which have been largely used in 
framing rations. In order to eliminate the size of the animal, 
the proportion of the various feed constituents, to be supplied 
daily for 1000 poimds of body weight, are given. For illustra- 
tion, a few standards are given here. (See full table in Ap- 
pendix.) 



236 



Agricultural Chemistry. 
For 1000 Pounds Live Weight Daily. 





Dry 
Sub- 
stance 


Digestible 


Nu- 




Protein 


Carbo- 
hydrates 


Fat 


tritive 
Ratio 


Cow, milk yield 22 lbs 

Fattening steer, 1st period.. 
Horse, medium work 


Lbs. 
29 
30 
24 


Lbs. 
2.5 
2.5 
2.0 


Lbs. 
13 
15 
11 


Lbs. 
0.5 
0.5 
0.6 


1:5.7 
1:6.5 
1:6.2 



In formulating standards for ruminants it is better to start 
with two kinds of roughage, furnishing from 16 to 20 pounds of 
dry matter, and about 10 pounds of carbohydrates (nitrogen 
free-extract), and then add concentrates, which will on first cal- 
culation bring the total digestible protein somewhat under the 
standard. The additional requirements can then be easily com- 
puted. The term "fat" is identical with the "ether extract." 

It is not necessary that a ration agree mathematically in all 
nutrients with the standard. To attempt to do this is to avoid 
the individual possibilities of the animal. The tables of digestion 
co-efficients and feeding standards are but averages and approx- 
imations. They are not to be followed blindly and absolutely, 
but if taken as guides, they can become extremely helpful. For 
example, the Wolff standards are quantities to be fed per thou- 
sand pounds of live weight. It is known that the food demands 
of an organism are not proportional to its size, but rather to its 
surface. This is because of a difference in demand on the heat 
producing function of a food. A small animal has a propor- 
tionately greater suface to its weight than a larger animal. Con- 
sequently it does not require the same proportional amount of 
digestible food to maintain a 1700 pound steer as one weighing 
]000 pounds. For instance, Kuhn of the IMockern Station, found 
that a 1900 pound ox could be maintained on 0.7 pound of di- 
gestible protein and 6.6 pounds of digestible carbohydrates. 



Feeding Standards. 237 

Other investigators have found that the Wolff allowances may be 
too high. Haecker of the Minnesota Station maintained a dry, 
barren cow of a 1000 pounds weight on 0.6 pound of digestible 
protein, 6 poimds of digestible carbohydrates, and 0.1 pound of 
digestible fat (ether extract). 

Energy value of feeds. The function of food, as has already 
been pointed out, is not only to repair waste and promote growth 
and increase, but also to furnish heat and energy. For this 
reason, attempts have been made by several investigators to assess 
the relative value of feeds by a determination of their heat pro- 
ducing power. Heat units are expressed either in starch equiv- 
alents or calories. The German investigators, Kellner and Zuntz, 
have used starch as the basis for expression, while Armsby of 
this coimtry is using the calorie. The calorie represents the 
quantity of heat required to raise the temperature of one gram 
of water from 0° to 1° C. A large Calorie, one thousand times 
larger than the small calorie, is usually employed for the ex- 
pression of large quantities of heat and will be used here, gen- 
erally. However, the new term, therm, which represents 1000 
large Calories, is now in use by Armsby and is the quantity of 
heat required to raise the temperature of 1000 kilograms of 
water 1° C. 

The value in large Calories of one gram of the several classes 
of nutrients, is given in the following table : 



Wheat gluten 5.8 

Animal muscle 5.7 

Starch 4.1 



Cellulose 4.1 

Cane sugar 4.0 

Animal fat 9.4 



Available energy. The data in the above table is secured by 
complete combustion of the material in the calorimeter. Such 
does not obtain in the animal body. It should be remembered 
that only part is digested, and as only the digested portion fur- 
nishes available energy, the available fuel value of a ration must 
depend primarily upon the amount which is dissolved out of the 
digestive tract and passes into the blood. There is fuel waste in 
the solid excrement of the feces, in the incompletely burned gases 



238 Agricultural Chemistry. 

escaping from the alimentary canal, and in the unoxidized com- 
pounds of the urine. It has been estimated by Kuhn that the 
loss of energy in the gas, methane, which has its source in the 
fermentations of the digestive tract, amounts to over one-seventh 
of the energy of the digested crude fiber and carbohydrates. 
From this we see that the available energy of a ration represents 
the fuel value of the dry matter digested from it, minus the 
energy in the dry matter of the urine and that lost in excreted 
gases. Such data have been secured on a number of materials 
by the use of the respiration apparatus — an air tight compart- 
ment in which the animal could live and from which the gases 
could be removed for analysis. At the same time the urine and 
feces could also be collected for a complete chemical analysis and 
for a determination of the energ}' still contained in them. 

Net available energy. We have seen that food is not applied 
to use until it reaches the blood. It must have work done upon 
it before it is in solution. The processes of mastication, of mov- 
ing it along the digestive tract, and of bringing it into solution 
all require the expenditure of a certain amount of energy. Zuntz. 
working with a horse, has attempted to measure this. His method 
has been to determine by various devices, how much more oxygen 
is consumed during mastication and digestion than before or 
after these operations are accomplished. From this measure of 
oxygen consumjjtion, he calculated the following heat units, rep- 
resenting the energy used in chewing certain feeds : 

Cal. 

1 pound corn. (454 grams) 0.3 

1 pound oats 21.0 

1 pound hay 76 .0 

This is an important finding. Zuntz calculates that in general 
the coarse feeds have 20 per cent less net energy value than the 
grains and that the work of mastication and digestion combined 
is about 48 per cent of the energy value of the digested material 
from hay and 19.7 per cent of that from oats. We must remem- 
ber, however, that the wastefulness of fibrous foods shown in 



Feeding Standards. 239 

these determinations on the horse are not true to an equal extent 
in the case of ruminants. In the latter the fiber is softened in the 
paunch and its digestion has begun before it reaches the intestines. 

Net available energy then, is the available energy minus the 
energy of digestion and preparation of the food for use. This 
internal work furnishes heat, and provided it is not in excess 
of the heat requirement of the animal, should not be regarded 
as waste. The waste of heat has begun when that produced by 
the work of digestion exceeds the animal requirement. But if it 
is produced in the digestive tract and not in the tissues of the 
animal, it cannot appear as useful work. 

We learn from this that it is not the total chemical energy in 
a feeding stuff which measures its value to the body, but that 
which remains after deducting the energy losses in the unbumed 
material of the excreta, the energy expended in digesting the real 
fuel materials from the food, and in addition, the energy used in 
transforming them into substances which the body can use or 
store up. This gives us what Kellner calls the productive value 
of feeds, and is identical in meaning with the term net available 
energy of feeds. 

Productive value of feeds. From elaborate experiments with 
the respiration chamber and mature oxen Kellner has determined 
the productive value of certain feeds. For this purpose he chose 
rather lean oxen, giving them a fixed moderate ration which re- 
sulted in a small increase in weight. He then added to the ration 
the feed to be experimented with, and determined the amount of 
increase produced. This was not done by weighing the animal, 
but by determining the amount of nitrogen and carbon retained 
by the animal. The protein tissue stored, was calculated from the 
nitrogen retained and the fat from the carbon left after deducting 
the carbon required to build the increase in protein. Kellner's 
results are shown in the following table . 

The available energy of these feeds had already been deter- 
mined and is given in the first column. In the second column 
appears the percentage of loss in the process of digestion and 



240 



Agricultural Chemistry. 



assimilation and production of tissue. The last two columns ex- 
press the energ}' value of the increase and the comparative pro- 
ductive value of the different materials, with starch as a unit. 
We see from this that 5C.3 per cent of the digested fat (peanut 
oil) was stored, and 44.7 per cent of the digested protein (wheat 
gluten), while but 17.8 per cent of the digested wheat straw was 
available for useful energy or increase. This gives us a scieji- 
tific explanation of the fact that coarse feeds are not adapted to 
rapid production. 

From such data Kellner concludes that 1 pound of digested 

Heat Values of Digested Feeds and of the Increase Obtained 
in a Fattening Ox. 



m 


Heat value 
to the ox of 

1 gram of 
digested 

substance 


Loss of 
energy in 
productive 
processes 


Heat value 

of increase 

obtained 


Comparative 
productive 

value. 
Starch 100 


Starch 


Cals. 
3.7 
3.6 
3 6 


Per cent 
41.1 
36.4 
36 i» 


Cals. 
2.2 ' 100 


Molasses 

Straw pulp . . • 


2.3 ! 104 
2 3 i 104 


Wheat gluten 


4.7 


.iS.T S 


2.1 f 101 


Peanut oil • . . . 


.S.8 43.7 

3.6 58.5 

3.7 62.4 
3.3 82 2 


4.9 224 


Meadow hay 


1.5 
1.4 
1.6 


68 


Oat straw 

Wheat straw 


6t 
27 











starch may yield a maximum of 0.23 pound of body fat, the rest 
being consumed in the transformation processes. Taking 1 pound 
of digestible starcli as his standard, he has formulated the relative 
values for the digestible nutrients in feeding stuffs, based on the 
amount of body fat the several pure nutrients would form if fed 
to the ox. 

Kellner's starch values. These are the values of the nutrients 
of feeds expressed with starch as a unit of energy. From the 
quantities of digestible nutrients in 1000 pounds of ordinary feed- 
ing material, the relative value of feeds for maintenance and 



Feeding Standards. 



241 



production in terms of starch have been calculated by Kellner. 
No extended table will be given here. However, to make this 
clear the digestible nutrients in a few common feeding materials 
are brought together in the following table. This table includes 
the amides, which are not, in American tables as a rule, dis- 
tinctly separated, but included under the term "crude protein" 
(NX 6.25). 



Pounds of Digestible Matter in 1000 Pounds of Various Feeds. 



Total 
organic 
matter 



Nitrogenous Substances 



Protein 



Amides 



Fat 


Carb. 


44 


651 


45 


441 


19 


fi07 


13 


269 


7 


163 


4 


150 



Fiber 



Corn 

Oats 

Barley 

Clover hay . . 

Oat straw 

Wheat straw 



786 
600 
715 
440 
381 
351 



73 

81 
70 
47 



4 
25 



12 

26 

15 

151 

199 

193 



From these data the maintenance value in terms of starch is 
made by the simple calculation: — Protein X 1-25 ^ + Amides X 
0.6 + Fat X 2.B + Carb. + Fiber. 

From this we see that the feeds for maintenance are valued at 
the full heat value of the digestible constituents. The heat which 
is the final outcome of the mechanical labor employed in digestion, 
can serve for warming the animal. But when the productive 
value is considered, it has been found that if we take only the 
digestihle fat. protein, and carbohydrates of the ration, and give 
to each the energy value found for it in Kellner 's production ex- 
periments, the sum of these will approximate the values actually 
obtained in the experiments tried. Consequently the productive 
value in terms of starch = Fat X 2.3 + Protein -J- Carb. 

iThe factors 1.25, 06, and 2.3 are those in use in Europe for converting 
the food constituents to an energy basis equivalent to starch. It should be 
observed that generally the factor 2.4 for fat is the only one used. 



242 



Agricultural Chemistry. 



In the following table are assembled a few examples of the 
starch equivalents of feeds for both maintenance and production, 
as formulated by Kellner. 



Comparative Value of Ordinarii Feeds for Oxen and Sheep- 



For Maintenance 



Value of 

1000 lbs. as 

starch 



Quantities 

equivalent 

to 1 lb. of 

starch 



For Production 



Value of 

1000 lbs. as 

starch 



Quantities 

equivalent 

to 1 lb. of 

starch 



Corn 

Oats 

Barley 

Clover hay. . 
O it straw. . . 
Wheat straw 



859 
676 
755 
459 
412 
357 



1.16 
1.48 
132 
2.18 
2.43 
2.80 



825 
626 
721 
319 
207 
96 



1.21 
1.60 
1.39 
3 13 
4.83 
10.41 



Kellner admits that our knowledge of the actual productive 
value of feeds is still very incomplete. Such values have been 
determined by actual experiments in only a few cases and then 
only for the mature fattening ox. It serves, however, to illus- 
trate the trend of experimentation and the serious and laborious 
attempts being made to place the nutritive value of feeding stuffs 
on a scientific experimental basis. It appears from the above 
table that approximatelj'^ 2 pounds of oat or wheat straw may 
replace 1 pound of com, if the ox or sheep is merely on a main- 
tenance diet, but that 1 pound of corn -will have as great an effect 
as 4 pounds of oat straw or 10 pounds of wheat straw when the 
animal must grow or fatten. 

Kellner's feeding standards. The first table on the following 
page is a brief summary of these standards. 

Armsby's feeding standards. As an outgrowth of the work 
of Kellner and continued work with the respiration calorimeter. 
Armbsy has begun to formulate feeding standards, giving the net 
productive energy of feeding stuffs. These are expressed in 



Feeding Standards. 243 

Standard Rations for 1000 Lbs. of Farm Animals. 





Dry 

matter 


Digestible Nutrients 




Proteins Starch value 


Maintenance of mature steers 

Fattening steers 


Lbs. 
15-21 
24-32 
25-29 
27-33 
18-25 
23-29 
33-37 
28-33 
24-28 


Lbs. 
0.6 

1.5-1.7 
1.6-1.9 
2.2-2.5 
1.0 
2.0 
3.0 
2.8 
2.0 


Lbs. 
6.0 
12.5-14.5 


Milch cow giving 20 lbs. milk daily. . . 
Milch cow giving 30 lbs. milk daily. . . 
Hors-e at light work 


9.8-11.2 
11.8-13.9 
9.2 


Horse at heavy work 


15 


Fattening swine Isl period 

Fattening swine 2nd period '. 


27.5 
26.1 


Fattening swine 3rd period 


19.8 







therms, and for illustration several examples are brought together 
in the following table. The complete table will be found in the 
appendix. 

Dry Matter, Digestible Protein and Energy Value in 100 Lbs. 



Feeding stuff 


Total 
dry matter 


Digestible 
protein 


Energy value 


Green al falfa 


Lbs. 
28 2 
91.6 
90.8 
89.1 
88.1 


Lbs. 

2.50 
6.93 
1.09 
6.79 
10.21 


Therms 
12 45 


Dry alfalfa 

Oat straw 


34.41 
21.21 


Corn meal 


88.84 


Wheat bran 


48.23 







The table is supposed to represent, with a fair degree of ac- 
curacy, the digestible protein and the net energy which the various 
feeding stuffs will supply. They express what is available to the 
animal for growth, fattening, work or milk production, after de- 
ducting that used in the work of mastication and assimilation. 
The digestible protein in the table is true protein and does not 
include the so-called "amides" of the "crude protein." 



244 



Agricultural Chemistry. 



Standards for maintenance. The following table shows the 
amount of digestible protein and net energy required per head 
for the maintenance of cattle, sheep and horses of different 
weights. No figures for swine are available. 

Armsby's Maintenance Standards for Horses, Cattle and Sheep. 





Horses 


Cattle 


Live 


Sheep 


Live 


1 


1 






weight 


Digest- 




Digest- 


j weight 


Digest- 






ible 


Energy 


ible Energy 




ible 


Energy 




protein 


value 


protein value 




protein 


value 


Lbs. 


Lbs. 


Therms 


Lbs. 


Therms 


Lbs. 


Lbs. 


Therms 


150 


.15 


1.70 


.30 


2.00 


20 


.02 


.30 


250 


.20 


2.40 


.40 


2.80 


40 


.05 


.54 


500 


.30 


3.80 


.60 


4.40 


60 


.07 


.71 


750 


.40 


4.95 


.80 


5.80 


80 


.09 


.S7 


1000 


• 50 


H.OO 


1.00 


7.00 


100 


.10 


1.00 


1250 


.60 


7.00 


1.20 


8.15 


120 


.11 


1.13 


1500 


.65 


7. '90 


1.30 


9.20 


140 


.13 


1.25 



From the table one sees that a colt of 500 lbs. weight will re- 
quire for daily support 0.3 lb. of digestible protein and 3.8 
therms, -vAhile when it has trebled its weight the requirements are 
0.65 lb. of digestible protein and 7.9 therms. In other words the 
requirements have not increased in proportion to the gain in 
weight. 

Standards for growing animals. The following table gives 
the digestible protein and energy required for gro\^'ing cattle and 
sheep, as set forth by Armsby. No data for horses and swine are 
available. The table includes the maintenance requirement. 

The table shows that a six months old calf, weighing 425 pounds 
requires 1 .3 pounds of digestible protein and 6 therms of energy 
value, which includes the 1.3 pounds of protein. Where the calf 
has grown to weigh 1100 pounds, or more than doubled its weight, 
it requires 0.35 pound more protein and 2 more therms. This 
relative lessening in feed required is due to the fact that a larger 



Feeding Standards. 



245 



animal requires relatively less for maintenance, and to the addi- 
tional fact that the rate of growth has greatly decreased. Armsby 
allows 1.75 pounds of digestible protein for a steer weighing 
1000 pounds, while but 1.65 is required when the same steer 
reaches 1100 pounds. This is due to the lessened increase in 
muscular tissue and consequently decreased demand for protein 
food, as compared with the earlier stages of life. It should be 
noted that in comparing maintenance and growing requirements, 
the larger part of all the food consumed is used for body support, 
and that additional requirements for growth are mainly in pro- 
tein, rather than therm requirements. 

Armsby's Standards for Growing Cattle and Sheep. 





Age 


Cattle 




Sheep 






Live 
weight 


Digest- 
ible 
protein 


Energy 
value 


Live 
weight 


Digest- 
ible 
protein 


Energy 
value 


3.. 


Months 


Lbs. 

275 
425 


Lbs. 
1.10 
1.30 


Therms 
5.0 
6.0 


Lbs. 

70 

90 

110 

130 

145 


Lbs. 

.30 
.25 
.23 
.23 
.22 


Therms 


6 

9 


1.30 
1.40 


12 

15 


650 


1.65 


7.0 


1.40 
1.50 


18 

24 

30 


S50 
1000 
1100 


1.70 
1.75 
1.65 


7.5 
S.O 
8.0 


1.60 



Standards for milch cows and fattening steers. In addition 
to the foregoing standards, Armsby recommends the following : 

1. For inilk production add to the maintenance standard 0.05 
pound of digestible protein and 0.3 therm for each pound of 
average milk containing 13 per cent of total solids and 4 per cent 
of fat. 

2. For fairly mature fattening cattle add 3.5 therms to the 
maintenance standard for each pound of gain in live weight. 

Armsb}^ does not provide additional protein to the maintenance 
standard for fattening steers, holding that if the proper allow- 



246 



Agricultural Chemistry. 



ance of therms is provided in addition to the maintenance ration, 
no additional protein is required for fattening purposes. On the 
other liand, for milk production the standard provides additional 
protein. This must be done because of the protein content of 
the milk itself and the additional factor of protein supply for 
the developing foetus. 

3. Armsby recommends that a 1000 pound ruminant should 
be given from 20 to 30 pounds of dry matter per day, while for 
the horse smaller amounts can be used. 

Standard for the working animal. The horse is the only ani- 
mal to be considered here. What applies to the horse may also 
be used for the mule. As a general average, Kellner recommends 
the following ration for a 1000 pound horse, the amounts stated 
including the maintenance requirement: — 

Requirements of the Working Horse. 



Digestible protein 



Energy value 



For light work .... 
For medium work 
tor heavy work. . 




Tlierms 
9.80 
12.40 
1(3.00 



Future of standards. The feeding standards being developed 
at the present time arc in a formative stage, and necessarily in- 
complete. No standard should be used as an exact mathematical 
expression of the animal 's needs. In fact it cannot be done, be- 
cause we are not in a position to know the exact requirements of 
the individual animal ; again, feeding stuffs of the same name 
show a considerable range in composition. Further, probably the 
most important factor in limiting the adoption of a feeding 
standard as a final recipe in feeding, is the difference in nutritive 
value and physiological action of the nutrients from various 
sources. One species of farm animal may do better on the nu- 
ti-ients from one specific source, as compared with those derived 



Feeding Standards. 247 

from another. In addition, the relative amounts and kinds of 
ash must be considered. The value of wheat bran does not re- 
side wholly in its protein content, but partly in its laxative prop- 
erties, which are due to a specific constituent, known as phytin. 
The superior value of legume hays must be attributed, in part, to 
their high lime content. This is particularly true when used for 
growing animals and milch cows. All these are factors to be 
reckoned with, but until they are completely worked out and 
catalogued, the student will still find the standards of "Wolff or 
Armsby helpful in formulating rations. 



CHAPTER XI 

FOOD REQUIREMENTS OF ANIMALS. 

The young growing animal. The distinct and characteristic 
feature of the growth of young animals is the rapid formation 
of soft tissue and bone. For this purpose there must be an 
abundant supply of protein and suitable ash. 

This is true for all young domestic animals. The daily in- 
crease in live weight of a well nourished calf is very considerable 
and may be as large as that of a well-fed, mature steer. It may 
amount to 2 pounds per day ; and much less than this would be 
regarded as unsatisfactory. Lawes and Gilbert analyzed the 
entire body of a fat calf with the following results : — 

Per cent 

Water 64.6 

Ash 4.8 

Protein 16.5 

Fat 14.1 

Based on this analysis the daily increase of 2 pounds live weight 
in a growing calf would-mean a storage of about 0.33 lb. of pro- 
tein and 0.28 lb. of actual fat, or a total increase of 0.61 lb. of 
dry body material. This may be equal to one-fifth or more of 
the total dry substance of the ration. European investigations 
with calves have shown that one pound of milk solids, practically 
all digestible, produced one pound of increase in live weight. Be- 
cause of the water content of this increase, the actual dry matter 
is equal to about one-third of a pound. Further, these studies 
showed that 70 per cent of the protein of the food was retained 
in the bodies of the calves and 72 per cent of the phosphoric acid 
and 97 per cent of the lime held for skeleton and tissue expansion. 
On an assumed consumption of 10 pounds of average milk daily, 
this would mean a retention of 6.4 grams (approximately one- 
fifth of an ounce) of phosphoric acid and 8.7 grams of lime. 



Food Requirements of Animals. 



249 



In this country, experiments with young lambs fed cow 's milk 
showed a gain in live weight of one pound for every 5.8 pounds 
of milk consumed. If the milk contained 13 per cent of drj^ 
matter, then 0.75 pound of milk solids produced 1 pound of in- 
crease. This is a high food efficiency and practically ten times 
that sho\Mi with animals somewhat mature. This serves to il- 
lustrate the rapid increase in tissue during the early periods of 
growth. 

The kind of food most appropriate to the wants of the young 
animal is revealed by the composition of milk. The first milk 
secreted by the mother (colostrum) is very rich in protein, often 
containing as high as 15 per cent. This gradually changes after 
parturition and after a lapse of 8 to 10 days the composition of 
the secretion becomes normal. Below is given the composition of 
colostrum and the normal milk of our common farm animals. 



Percentage Composition of Colostrum Milk. 





Water 


Protein 


Fat 


Sugar 


Ash 


Nu- 
tritive 
ratio 


Ewe 

Sow 

Cow 


66.4 
70.1 

74.7 


16.6 
15.6 
17.6 


10.8 
9.5 
3.6 


5.0 

3.S 
2.6 


1.2 
0.9 
1.5 


1:1.8 
1:1.6 
1:0.6 





Percentage Composition of Milk. 



Ewe . 
Sow . . 
Cow . 
Mare. 



80.8 


4.9 


6 . 9 


4.9 


.84 


1: 


84.6 


5.2 


4.8 


3.2 


.80 


1: 


87.0 


3.5 


3.9 


4.8 


.70 


1:. 


90.8 


2.0 


1.2 


5.6 


.40 


1: 



3.1 

2.2 



The solid matter of milk has a high feeding value, because of 
its complete utilization by the animal. It also supplies an abun- 
dant amount of ash material for skeleton and tissue formation. 
That each species has provided for the young a milk of such pro- 



250 Agricultural Chemistry. 

tein and ash content as will meet the rate of development char- 
acteristic for that species is seen in the following table: — 

Days required 
Protein Ash to double weight 

Ewe 4.i» per cent 0.84 per cent 15 

Sow 5.2 " " 0.80 " " 14 

Cow 3.5 " " 0.70 " " 47 

Mare 2.0 " " 0.40 " " CO 

Human 1.6 '• " 0.20 " " ISO 

This is a very suggestive relation of the protein and ash content 
of milk to the rate of growth and serves to illustrate the necessity 
of maintaining a liberal supply of these materials in easily avail- 
able form for the growing young. It is also necessary to remem- 
ber that approximately 50 per cent of the ash of milk is made 
up of the bone-forming constituents, lime and phosphoric acid. 
This emphasizes the desirability of maintaining the supply of 
these ash constituents in the feed of the animal as the mother's 
milk is withdrawn and other feeds substituted. 

Supply of ash material necessary. Probably no class of farm 
animals is exposed to as much danger in this regard as the pig. 
Abundant supplies of lime, in particular, are contained in the 
hays and leafy parts of plants, but these, normally, do not form 
a part of the ration of this species of farm animals. The grains 
are low in lime; and even wheat bran, so often accredited mth 
abundant bone forming materials, is relatively low in lime. It 
contains an abundant supply of phosphorus, and in so far as 
the supply of this element is concerned, normal rations for all 
classes of farm animals, of which the grains and particularly 
wheat bran form a part, will generally supply a sufficient quan- 
tity. In furnishing an abundant natural supply of lime to the 
growing animal, recourse may be had to the legume hays for 
ruminants or the ground meal from alfalfa or clover hay for th(> 
young pig. 

The meadow havs are also i-ich in lime, but do not contain as 



Food Bequirements of Animals. 251 

much as the le^me hays. The beneficial use of wood ashes, as 
a supplement to com in the ration of pigs, probably lies, in part 
at least, in its high lime content. The use of artificial sources of 
lime for growing animals of all classes, where the natural sources 
are not available, is highly justifiable. Probably lime as a phos- 
phate serves this purpose best, and either what is called pre- 
cipitated calcium phosphate or the crude, finely ground phosphate 
known as ''floats" can be used to advantage. About i^ to i/o of 
an oimce per 100 pounds of live weight during the rapidly grow- 
ing periods should serve the purpose of building a strong skeleton. 




The effect ol' impropeiij' balanced rations on growing animals. The ra- 
tion fed these pigs was too low in phosphorus. 

No attempt is made here to give directions for feeding animals : 
this must be sought for in texts wholly devoted to that subject. 
Only a few of the more fundamental principles are discussed. 

Dangers from too rich milk. In recognizing the mother's milk 
as supplying the nutrients in the best forms and proportions, it 
is necessary^ to add that milks very rich in fat have been found 
to cause intestinal disturbances and impaired nutrition. This is 
not only true of cow 's milk fed the calf, but also true when that 
milk is fed to pigs or to the human infant. 

The following explanation for this harmful effect of excess of 
fat in the food has been offered: — The general capacity of an 
organism for the absorption of fat is strictly confined within nar- 
row limits and consequently an excessive supply is not absorbed. 



252 Agricultural Chemistry. 

but remains in the intestine. There it is converted into soaps, 
composed of part of the fat and an alkali, and as such eliminated 
from the body in the excreta. This excretion of soap entails to 
the body a heavy loss of alkaline bases, which when continued for 
some time results in disturbed nutrition. On an exclusive milk 
diet containing 3.5 per cent of fat the supply of alkaline bases ip 
only sufficient for normal development and the production of fat- 
rich milk in cows is not attended by a corresponding increase in 
the ash forming materials. Rich milk is the result of breeding 
by man and is not a condition original to the milk of the cow. 

Another important fact to bear in mind is that the capacity to 
digest the starchj'' grains and similar substances is somewhat un- 
developed in the very young animal and that the ferments neces- 
sary for this purpose are probably not yet very abundant. For 
this reason the first substitute for milk should not consist too 
largely of cereal grains, or concoctions of insoluble, starchy ma- 
terials. Bulky, fibrous food is likewise unsuitable for the young 
animal. The digestive tract of calves and colts must gradually 
expand before the coarse hays can form a large part of their ra- 
tion. 

Influence of food. In experiments on the influence of food 
upon the development of the animal body, some interesting results 
have been recorded. Sanborn and Henry fed to swine rations 
varying considerably in the protein and ash supply. Comparisons 
of middlings and blood against com meal alone, or shorts and bran 
against potatoes, tallow and com meal, showed considerable dif- 
ferences in the development of the animal. Those fed high nitro- 
genous rations contained more blood than the others, while such 
organs as the kidney and liver were larger in proportion to the 
weight of the body, the bones stronger, and the proportion of 
muscle greater. These were extreme rations, and not likely to 
occur in practice, but the experiment serves the purpose of em- 
phasizing the necessity of an abundant supply of protein and ash 
material for the growing young. Swine fed on corn and gluten 
feed, against com, gluten feed and ' ' floats ' ' have sho^^^l marked 



Food Requirements of Animals. 253 

differences in the skeleton development. In this experiment the 
proteins were abundantly supplied in both rations, but only in the 
second was there a liberal supply of lime and phosphoric acid. 
Where such a supply was maintained the skeletons were large 
and strong. 

Jordan fed two lots of steers from calf -hood on rations widely 
different in their nutritive ratio. The one lot received for grain, 
oil meal, wheat bran and corn meal, and the other lot com meal, 
with a minimum proportion of wheat bran. A nutritive ratio of 
1 :5.2 and 1 :9.7 was maintained. At the end of 17 months and 
27 months, one animal from each lot was killed and the entire 
body, exclusive of hide, analyzed. There was no material differ- 
ence in the composition of the animals. ' ' The amount of growth 
was at first more rapid with the more nitrogenous ration, but the 
kind of growth appeared to have been controlled by the somewhat 
fixed constitutional habits of the breed." (Jordan.) 

It is sometimes claimed by practical men that feeds nch in bone- 
forming materials should be withheld from the pregnant mother; 
that such feeds are conducive to large boned offspring, making it 
difficult for the young to be bom. Little data on this question 
are available, but from some experiments on swine at the Wis- 
consin Station, there is no evidence that excessive supplies of bnne- 
forming materials influence the size or the ash content of the 
skeleton of the newly born. It appears that the power to main- 
tain a constant composition for the foetus, independent of wide 
variations in food supply, lies inherent in the mother. 

The adult animal and food for maintenance. The food of an 
adult animal, neither gaining nor losing in weight, is used for 
renewal of waste tissue, the growth of hair, horn and wool, and 
for the production of heat and mechanical work. The work per- 
formed consists in the muscular movements involved in chewing 
and moving the food along the intestinal tract; muscular move- 
ments of the heart in pumping the blood; respiration and the 
metabolic activity of the cells in causing the chemical transforma- 
tions of the nutrients. This is intemal work. It has been eal- 



254 



Agricultural Chemistry. 



culated that the power exerted daily by the heart of a man 150 lbs. 
in weight, would raise 1 ton to a height of 242 feet. Then in ad- 
dition, there is always some Avork done in moving the body from 
place to place. A horse of 1100 pounds weight, walking 20 miles 
on level ground, and without a load, will do work equivalent to 
raising 2328 tons 1 foot. The internal work finally appears 
largely as heat, while in the external movements of the body, 
probably 70 per cent of the total energy developed in the muscle* 
appears as heat. 

The smaller the animal the greater the loss of heat per u;iit of 
weight, and consequently the more liberal must be the supply of 
food. This is because small bodies have in proportion to their 
weight, a much greater surface. Thus, heat is lost by radiation 
from the surface of the body and in evaporating the water ex- 
haled through the lungs and skin. 

In the following table the heat production in resting animals 
is given: — 

Heat Production in Resting Anivials. 



N 


Weight 
in pounds 


Calories produced 




p-p-d ^'is,.r- 


Horse 

Pig 

Dog 

Goose 


970.0 

2.S1.0 

33 

7 . 7 

0.03 


24.8 

42.0 

103.0 

146.7 

466.0 


948 
1078 
1039 

943 


Mouse 


917 







This shows that animals Avill produce heat in proportion to 
their surface ; it is interesting to note that in the standard rations 
for animals, the quantity of food increases at nearly the same 
ratio as the surface increases. For example, while the oxen in 
growing from a weight of 165 to 935 pounds increases in weight 
5.7 times, the surface of the animal increases but 3.2 times and 
the food required, 3.5 times. 



Food Requirements of Animals. 255 

It is essential that the maintenance ration should supply enough 
protein to replace the daily waste of the nitrogenous tissue. Only 
a small amount is necessarily destroyed by the resting animal : 
but there is a constant waste, and unless this is replaced the 
animal will die of stain^ation. It is plain then that the demands 
upon food for maintenance purposes are mainly for the produc- 
tion of muscular energy and heat. Armsby found that a supply 
of 0.6 lb. of digestible protein per day was sufficient for the 
permanent maintenance of a 1000 pound ox, receiving a ration 
with a nutritive ratio of 1:11. 

The thorough studies of Zuntz on the horse have shown that a 
1000 pound animal can be maintained on 6.4 pounds of available 
nutrients, provided the total ration does not contain more than 
three pounds of crude fiber. This means that the nutrients must 
come from hay and grain. Grandeau places the maintenance re- 
quirement for the same weight of animal at 7 to 7.8 pounds of 
digestible organic matter, including 0.45 pound of digestible pro- 
tein. 

There are few experiments with sheep, but according to German 
experiments, 11.8 pounds of digestible organic matter, including 
] .0 pound of digestible protein, per 1000 pounds live weight are 
required to maintain proper conditions. Its continued produc- 
tion of wool, higher temperature and smaller size make the re- 
quirements for this animal somewhat more liberal than with the 
horse or ox. 

It is clear then that 90 per cent or more of a maintenance ration 
may consist of carbohydrates or materials used solely for fuel. 
This makes it easy to supply this ration from the home grown 
products. The quantity of available nutrients consumed is small 
and may largely be made up of coarse material, such as corn 
fodder and hay. Again, the low protein requirement and the pos- 
sibility of a Avide nutritive ratio, characteristic of home grown 
products, makes its selection easy. 

Requirements for labor. As the horse is practically the only 
animal used in this country for draft and road purposes, it will 



256 Agricultural Chemistry. 

be considered alone in this connection. The source of the energy- 
evolved during labor and appearing as extra work and heat must 
come from the oxidation of food. If work is to be performed 
and at the same time body weight remain constant, the quantity 
of food must be increased. 

It was supposed at one time that muscular effort was produced 
by the oxidation of the nitrogenous constituents of the muscle, 
and that a ration very rich in protein was necessary, if hard work 
was to be maintained. This idea is now known to be erroneous. 
Men have climbed mountains and measured the excretion of urea 
(the principal nitrogenous constituent of the urine) during such 
severe exercise. There was no important increase in its produc- 
tion under such conditions. Increased work increases the excre- 
tion of carbon dioxide but not of nitrogen. In other words, the 
carbohydrates and fats are largely the fuel materials that furnish 
energy for mechanical purposes. 

Zuntz has determined the quantity of food which a horse needs 
in order to perform work under varying conditions. "A horse 
weighing with harness 1144 pounds, will require 1.33 pounds of 
available food to walk 10 miles at 2i/^ miles per hour; 1.69 pounds 
when walking the same distance at a speed of 3 1/3 miles per 
hour ; and 2.53 pounds when trotting the same distance at 7 miles 
an hour. ' ' This is important knowledge on the influence of speed 
upon the food requirement in a unit of time. 

The pace of the animal is another important factor. Grandeau 
and Leclerc kept a horse in good condition, walking 12^ miles 
a day with a daily ration of 10.4 pounds of hay. but when the 
same distance was done trotting, 24 pounds was insufficient, A 
horse walking the above distance and hauling a load (equivalent 
in additional work to 1943 foot-tons) was maintained by a ration 
of 26.4 pounds of hay ; but when the same work was done trotting, 
a daily ration of 32.6 pounds of hay, which was all it would eat. 
was insufficient to maintain weight. Trotting or galloping in- 
volves additional internal work ; the animal also lifts its own 
weight at each step, which only appears as heat as it falls back 



Food Requirements of Animals. 257 

again. Consequently horses of different "action" wdll require 
unlike amounts of food to aecomplisli the same task. 

When a horse exerts itself to the utmost the consumption of 
oxygen rises rapidly and the food consumed per unit of work may 
be nearly twice as much as with ordinarj'' draft. A slow pace, 
consistent with conditions involved, will be economical of food 
consumption per unit of work performed. 

Zuntz found that the requirements for a horse, plowing 8 hours 
a day, were 14.03 pounds of digestible nutrients. This is some- 
what less than the requirement found in the German standards of 
Wolff and Lehmann. According to these formulas, a 1000 pound 
liorse requires 11.4 pounds of digestible food daily for moderate 
work, 13.6 pounds for average work, and 16.6 pounds for heavy 
work. These standards also call for a nutritive ratio of 1 :7 to 
] :6, dependent upon the severity of the labor. On the other 
hand, Lavalard, recommends that 1.15 pounds of digestible pro- 
tein daily is sufficient for ordinary labor, and 1.35 pounds when 
the labor is severe. This is a nutritive ratio not far from 1 :10. 
From what has been said on the source of muscular force, it is 
probable that the nutritive ratio recommended by the German 
standard is narrower than need be. Horses working on the sugar 
l)lantations of the Fiji islands receive 15 pounds of molasses per 
day and a nutritive ratio of 1 :11.8. However, a fairly good pro- 
portion of protein, for its peculiar and characteristic dynamic 
effect, appears advisable. 

It is the opinion of Jordan that ' ' rations properly compounded 
from ordinary farm products, such as silage, roots, meadow hay, 
legume hays and the cereal grains, will generally contain protein 
in sufficient proportion and will seldom need reinforcing with the 
commercial nitrogenous feeding stuffs. ' ' 

If a horse at severe labor requires 16.6 pounds of digestible 
nutrients, it is manifest that this could not be obtained from the 
coarse fodders. Concentrated feeds must be used. Ten pounds 
of hay is all a work horse should consume in one day. We have 
seen that the productive value of the coarse feeds is not as large 



258 Agricultural Chemistry. 

as the grains, and consequently cannot be expected to furnish 
available energy for severe labor in sufficient quantity, compatible 
with the storage capacity of the digestive apparatus of the horse. 

There has been a strongly established opinion that oats are 
pre-eminently the horse feed and must form a generous propor- 
tion of the grain ration ; that they give life and nerve to the 
animal. At one time the discovery of a special compound, 
''Avenin,'' resident in the oat kernel and endowed with these 
stimulating properties, was announced. Tliis is now disproved 
and it is becoming more and more evident that other grains can be 
substituted for oats with no impairment to the animal's well 
being. 

Fattening requirements. To increase body weight it is neces- 
sary that the food supply be in excess of that required for main- 
tenance and for the production of heat and work. When such 
an excess is given, the protein and ash are in part converted into 
new tissue, and the fats, carbohydrates and possibly proteins, 
stored up in the form of fat. Feeding a yoimg animal an excess 
will promote the further development of bone and muscle, while 
in the case of the mature animal, the increase wiW come almost 
wholly from the deposition of fat in the tissues. In both in- 
stances fat forms the largest proportion of the increase. This is 
shown in the following figures : — 

Composition of Increase When Steers are Fattening. 

Water Ash Protein Fat 
Per cent Per cent Per cent Per cent 

Oxen, fattening very youn^r 3^2-'^7 2.2r> 10 50-55 

Matured animals, final period.. 25-.S0 1.5 7-8 60-65 

These figures serve to illustrate how the food is used, and that 
the increase is largely fat formation. A satisfactory gain of 2 
pounds per day would then mean a storage of 1.3 to 1.5 pounds 
of dry substance, of which about 0.2 pound is protein. From the 
fact that carbohydrates can serve as sources of fat, it is evident 
that the non-protein part of a ration may be the chief source of 
the increase laid on by a fattening animal. The protein require- 



Food Requirements of Animals. 259 

ment for the constructive work is apparently small. It would 
appear from this that the nutrients serving mainly for fat forma- 
tion need not come from proteins in the ration, but rather from 
the fats and carbohydrates. Further, from a theoretical point of 
view, this would lead us to the conclusion, that for fairly mature 
fattening animals the nutritive ratio may be wider than that 
recommended in the German standards. These standards call 
for a ratio of from 1 :5 to 1 :7 in the various classes of fattening 
farm animals. 

KelLner, from experiments on oxen, declares that a fattening 
ration may vary in its nutritive ratio from 1 :4 to 1 :10 without 
alfecting the amount of increase per unit of digestible matter, 
provided the nutrients supplied above maintenance come from 
easily digestible feeding stuffs. Armsby, in his standards for 
fattening steers, provides no additional protein above mainte- 
nance, only allowing additional therms, which simply represent 
material for fuel and fat formation. Certain practical feeding ex- 
periments show that wide rations have been as effective a.s the 
narrower ones. On the other hand there are experiments of this 
class which show more rapid gains when a larger proportion of 
protein was furnished. Possibly these are to be explained on the 
basis of increased palatability and variety of nutrients, thereby 
securing an increased consumption. The proportion of protein 
was probably a minor factor. When the nutrients supplied secure 
palatability, ease of digestion and bowel regulation, it is probable 
that they need not be of very highly nitrogenous character. 

Facts bearing on this point are disclosed in the pig feeding ex- 
periments at the Rothamsted Station and are appended in the 
following table. 

The figures in the last column are not the nutritive ratios, 
which apply to digestible matter, but simply the ratios of nitro- 
genous to non-nitrogenous matter. The true nutritive ratio would 
be considerably wider. The results clearly show that 100 pounds 
of increase were produced with practically the same consumption 



260 



Agricultural Chemistry. 



of organic matter, notwithstanding the great variations in the 
(juantity of protein supplied. 

In the case of sheep, the fattening process is not greatly unlike 
that of steers, the increase being, however, somewhat richer in 
fat. 

It is probable then, that for fattening animals a nutritive ratio 
somewhat under that recommended by the Wolff standards is not 
inconsistent with successful feeding. However, if the animal is 
still growing, then it is apparent that a wide ratio is not con- 



Fattening Pigs on Food Rich and Poor in Protein. 





Consumed to produce 100 lbs. 
of gain 


Ratio of 
protein to 
non- 
protein 


Food Supplied 


Protein 
substance 


Non- 
protein 
substance 


Total 
organic 
matter 


Benns and lentil meal 


Lbs. 
137 
113 
81 
80 
72 
72 
58 


Lbs. 
291 
297 
329 
340 
338 
360 
362 


Lbs. 
428 
410 
410 
420 
410 
438 
420 


1:2.1 


Bean.«, lentil and corn 

Starch, sugar, lentil, bran 

Starch, lentil, bran 

Corn, bean, lentil, bran 


1:2.6 
1:4.1 
1:4.2 
1:4.7 
1 :5 . 1 


Corn and bran 


1:6.3 







ducive to best results. From this it follows that the home grown 
fodders and grains can furnish the main sources of the nutrients 
required for fattening purposes. It must always be kept in mind, 
however, that mere mathematical fornmlas should not form the 
basis for calculating supplies for the living organism. The feeder 
recognizes the value of a little oil meal and middlings in keeping 
the animal in ''condition" for best results, but it is not to be 
assumed that their entire value lies in their protein content. The 
economy of a ration may not always depend upon its capacity to 
form an increase. It may be decidedly to the farmer's advantage 
to enrich the food with such materials as bran and highly nitro- 



Food Bequirements of Animals. 



261 



genous foods for the purpose of increasing the value of the manure 
produced, and in this way to maintain and increase the fertility 
of the land. 

Before leaving this subject it may be valuable to call attention 
to the relative efficiency of the different classes of farm animals 
as transformers of food into body increase. Warington furnishes 
some interesting data on this point : — 



Per 1000 lbs. live 


weight 


per week 




Dry 


Digested 


Increase 


matter 


organic 


in live 


consumed 


matter 


weight 


Lbs. 


Lbs. 


Lbs. 


125 


88 


11.3 


160 


121 


17.6 


270 


227 


64.3 



Required to produce 
100 pounds increase 



Dry food 
consumed 



Digested 
organic 
matter , 



Oxen. 
Sheep 
Pigs . . 



Lbs. 

1,109 
912 
420 



Lbs. 
777 
68() 
353 



It will be seen that in proportion to its weight, the sheep eats 
more food and yields more increase than the ox, while the pig 
consumes more food and returns much more increase than either. 
This is due to the concentrated and easily digestible character of 
the food supplied the fattening pig. It must expend compara- 
tively little energy in preparing the material for assimilation. 
Again, the digestive apparatus of ruminants is anatomically dif- 
ferent from that of the pig. In the former the capacity for the 
storage of rough fodders is large, but the proportion of intestine, 
where absorption is most active, is much smaller than in the pig. 

Requirements for wool production. "Wool is the hair of sheep : 
but the hair of certain goats, such as the alpaca, cashmere, and 
mohair, as well as that of the camel, is also classed as wool. Wool 
differs from ordinary hair only in its physical structure, being 
covered with minute, overlapping scales, and having a twisted 
or curled fiber. Wool has great affinity for water and may con- 
tain from 8 to 12 per cent of moisture in hot, dry weather, and up 



2'62 Agricultural Chemistry. 

to 50 per cent in damp weather. Raw wool consists of (1) yolk 
or wool-grease; (2) suint; and (3 J the pure wool hair. The first 
two may constitute from 30 to 80 per cent of the weight of the 
unwashed wool. The yolk is made up of fatty or wax-like bodies, 
of complex composition and insoluble in water. In a washed 
tleeee the yolk may vary from more than 30 per cent to less than 
8 per cent. Short fine wool contains the largest proportion of 
yolk. The suint is an excretion of the perspiration glands of the 
skin and consists of potassium salts of fatty acids, together with 
phosphates, sulphates and chlorides. It is soluble in water and 
consequently, removed by washing. It jnay amount to 50 per cent 
of the weight of unwashed wool, but with a sheep exposed to the 
weather, the quantity may be 15 per cent or less. 

The pure wool fiber is, for the most jiart, a protein and contains 
about 16 per cent of nitrogen and 3.6 per cent of sulphur. A 
large proportion of the nitrogen of a sheep 's body is found in the 
wool. The fact that wool production is at the expense of proteins 
must indicate that a somewhat narrower ration is demanded than 
for mere fattening. Wolfi: fed two sheep on rations consisting of 
hay and bean meal, which supplied proteins liberally and main- 
tained the weights of the animals. Two others received at the 
same time, oat straw and roots, and lost slightly in weight. The 
yield of pure wool fiber in the first case was 12.9 pounds and in 
the second 10.0 pounds. It appears from this that under poor 
treatment the yield of wool will be seriously diminished. Ex- 
periments further show that on liberal fattening rations, the pro 
duction of wool is no greater than when tlie ration is just sufficient 
to maintain tbe animal. However, from the oxpi'riments of otbei"s. 
it appears that on somewhat scanty rations, the body may lose 
weight without the production of wool being seriously affected. 
All this emphasizes the fact that for the liealth and vigor of the 
animal producing this nitrogenous coat, the protein supply must 
not fall too low. 

The high favor in which such root crops as turnips and ruta- 
bagas are held by sheep feeders may find its explanation in their 



Food Bequirements of Animals. 263 

richness in sulphur, which we have seen constitutes a considerable 
proportion of the pure wool fiber. 

Requirements for milk production. Milk ultimately comes 
from the food and its direct purpose is for the nutrition of the 
young. For this reason its production, so far as possible, is made 
independent of the immediate food supply. If the surplus food 
given a fattening ox is withdrawn to a maintenance requirement, 
the laying on of increase will immediately cease ; but the food of 
a milking cow may be reduced to maintenance, Avithout stopping 
the production of milk. The animal will continue to produce 
milk, drawing for its source from her own body. The quantity 
produced will decrease and the arjimal will steadily grow thinner. 
A minimum food supply M-ill not entirely stop milk production, 
neither will an over-abundant supply raise the milk production 
beyond certain limits. Each cow has an inherent milk producing 
capacity, determined by breed and individuality. Above this it 
is rarely possible to go, but whether this capacity is reached will 
depend upon food and treatment. Excess of food will simply 
tend to fatten. Generous feeding will not make a good milch cow 
out of a poor one, but it will sustain a full flow of milk and extend 
the period of profitable production. 

There is only one way to determine whether a cow is profitable, 
and that is by determining her yield of milk and the amount of 
marketable constituents it contains. To-day, this is entirely done 
on the basis of the quantity of fat the milk contains, which gives 
the animal's capacity for butter production. To measure the 
capacity of her milk for cheese production, both fat and casein 
must be determined. From the standpoint of economy in trans- 
forming feed stuffs into human food, the total milk solids, and 
not the milk volume, should be the basis for estimation. 

The quantity of nutrients necessary to make 100 pounds of 
Jersey milk, other things being equal, is greater than that re- 
quired to produce the same weight of Holstein milk. From the 
standpoint of the farmer the most profitable cow is the one pro- 



2G4 Agricultural Chemistry. 

ducing the largest return in butter fat," butter fat and casein, or 

total milk solids j)er unit of food consumed. 

The transformation of digestible feed material into human food 

by the dairy cow far exceeds that produced in the same time by 

the growing or fattening ox and slightly exceeds that produced in 

swine. An ox, gaining 2 pounds per day, will yield in edible 

solids about 1.5 pounds, while a dairy cow, producing 30 pounds 

of milk containing 12 per cent of solids, will yield 3.6 pounds. 

Based on pounds of digestible nutrients consumed, Jordan has 

given us some interesting figures. They are general averages 

and are given in the following table ; they represent the pounds 

of edible solids produced by 100 lbs. of digestible organic matter 

in the ration. 

Relation of Food to Produce. 

Edible solids 

Lbs. 

Milk 18.0 

Steers, (carcass) 2.52 

Lambs 2.60 

Swine 15. GO 

Calves 8.10 

Fowl 4.20 

Eggs 5.10 

The quantity of solids in the cow's milk, per unit of feed con- 
sumed, thus always exceeds the quantity of solids produced in 
the increase of the fattening ox, and in the order of food effi- 
ciency the cow leads the list. 

Milk is a highly nitrogenous substance, and its proteins must 
be made from protein. They can have no other ultimate source 
but the feed and cannot be produced from fats or carbohydrates. 
Thirty pounds of average milk will contain a pound of protein. 
This daily drain means that the ration of the daiiy cow must 
be reasonablj'' narrow. If 0.6 pound of protein is needed for 
maintenance, then 1.6 pounds must be used daily. Practice and 
science have established the quantity of digestible organic matter 



Food Requirements of Animals. 265 

necessary for economical milk production at from 15.5 to 16.5 
pounds per day for a good cow of average size. The quantity re- 
quired may vary somewhat according to size, — a small cow re- 
quiring proportionately somewhat more than a larger one for the 
same yield of milk, — but capacity for production is the more im- 
portant factor in determining the quantity of feed required. 
With that amount of digestible nutrients, the nutritive ratio 
would be about 1 :9.5. Careful experiments, however, show that 
a nutritive ratio of 1 :5.5 to 1 :6.5 is more efficient than the wider 
one, and that a cow of average size and good capacity should re- 
ceive at least 2.25 pounds of digestible protein daily, with a nu- 
tritive ratio not wider than 1 :6.5. Young pasture grass, well 
known to be an efficient milk producer, is even narrower than this. 
The fimction of this additional protein is not known, but the ac- 
cepted axiom that proteins stimulate the metabolic activities of 
the cells is borne out here, with an intensified milk secretion as 
the result. On the other hand, excessive protein feeding may 
be injurious and certainly is not necessary. 

It has been taught that the fats of milk originate from the 
protein and food fats. If true, this would increase the demand 
for protein, but experiments have clearly demonstrated that they 
are not a necessary source of milk fat. In a carefully conducted 
experiment at the New York Experiment Station, Jordan con- 
clusively showed that the carbohydrates of the food could serve 
as milk-fat formers. 

The food consumed by the dairy cow during the first half of 
the lactation period is largely used in milk production, but during 
the latter portion of lactation it is partly consumed in building 
the calf, and the return in milk is reduced. A newly-born calf 
weighing SO pounds, may contain 20 pounds of protein, 3 pounds 
of fat, and the rest will be water and ash. 

From what has been said on the necessity of a proper protein 
supply for the milch cow, it is apparent that where the home 
gro^^^l crops are the hays made from true grasses and where the 
com crop is the chief one raised, then home-grown rations for 



2()C) Agricultural Chrmiftfry. 



1 



maximum efficiency in milk prodnction are not possible. Where, 
however, alfalfa and clover make the hay. and peas and oats are 
grown, a protein supply consistent with efficiency can be pro- 
duced. 

There is the additional fact that the production of milk de- 
mands a plentiful ash supply to the animal. Thirty pounds of 
milk will contain nearly an ounce of lime and the same quantity 
of phosphoric acid. Besides the quantities secreted in the milk, 
there is apparently a waste from cell activity, which in the case 
of a dairy cow yielding 30 pounds of milk, was found to be nearly 
equal to the quantity secreted in the milk. In an experiment at 
the AVisconsin Station, where a ration was made up of oat straw, 
rice, wheat brMn and wheat gluten, a cow continued to give a milk 
of constant composition in respect to lime content, as well as all 
other constituents ; yet the amount of lime supplied the animal, 
for a period of over 100 days, had been deficient. To maintain a 
normal composition of the milk, the animal had withdrawn lime 
from her skeleton, a remarkable transmigration of material. The 
health of the animal was apparently unimpaired, but it is self- 
evident that ultimately the milk flow must have ceased or the 
animal would have collapsed. While the ration used was unusual, 
the experiment, however, emphasizes the necessity of a liberal 
supply of ash material for the dairy cow. The legume seeds and 
cereal grains are low in lime, but are fairly rich in phosphorus. 
Wheat bran is relatively poor in lime, but rich in phosphorus. 
Ten poimds of bran will supply about one-fourth of an ounce of 
lime, but nearly one-third of a pound of phosphoric adid. The 
hays from the true grasses are faii-ly well supjilied with lime, 
but the legume hays, as clover and alfalfa, are particularly ricli 
in this material, and should, for this reason, fonii a part of the 
ralion of thn dairy cow. 

It would appeal", then, that in most latious recognized by 
dairymen as et'(ici«'nt foi- milk production, phosphoric acid and 
lime will be plentifully supplied, especially where bran and the 
legume hays constitute a part of the ration. But should straws 
foi'iii the I'ougbage. the supi)ly of liiiK^ juay become deficient. 



CHAPTER XII 

MILK AND ITS PRODUCTS. 

Milk is a valuable agricultural product and both it and the 
products obtained from it are of considerable commercial and in- 
dustrial importance. The dairy products of the State of Wis- 
consin alone are valued at $75,000,000. 

Secretion. Milk is the secretion of special glands in the mam- 
malian female and adapted to the nourishment of the newly born 
young of that particular species. The constituents of the milk 
are especially elaborated by the cells of the mamma; these con- 
stituents do not exist preformed in the blood, but are formed by 
profound chemical processes, little understood, out of the nu- 
trients carried in the blood to the active cells. For example, no 
casein or milk sugar exists either in the food of the cow or in her 
blood, but from the nitrogenous constituents of blood, the com- 
plex protein, casein, is elaborated; also, from the simple sugar 
dextrose, the more complex milk sugar is formed. This is all 
accomplished through the wonderful activities of the udder cells. 
That the composition of the milk is closely related to the food re- 
quirements of the newly born young and its rate of growth, has 
been suggested by the physiologist, Bunge. This relates partic- 
ularly to the ash and protein materials of milk, which are so 
necessary for the life processes and the rapid building of the 
growing young. 

The following table will clearly show that the ash of milk and 
of the new born young are very much alike, while they have an 
entirely different composition from the fluid out of which they 
are formed, namely the blood, and especially the blood serum: 
from a consideration of such facts, it appears certain that the 
cells of the milk gland must possess the power of selection and 
that milk is not merely filtered from the blood. 



268 Agricultural Chemistry. 

Comparative Compoaition of the Milk, Blood and Body 
of the Same Animal. 



1 





100 Parts by weight of ash contained in grains 




Dog a few 
hours old 


Dog's milk Dog's blood 


Dog's blood 
serum 


Potash 


11.14 
10.6 
29.5 
1.8 
39.4 


15.0 

8.8 

27.2 


3 1 ^4. 


Soda 

Lime 


45.6 
9 


52.1 
2.1 


Magnesia 

Phosphoric acid 


1.5 
34.2 


0.4 
13.3 


0.5 
5.9 



If we compare the time required by the suckling to double 
its weight at birth, with the amounts of protein and ash — per- 
haps the most essential constituents for the formation of tissue — 
contained in 100 parts of milk, it is evident at a glance that the 
amounts of these' increase in proportion to the rate of growth of 
the animal. This is shown in the following table : — 

Composition of Milk Ash from Different Aiiimals. 



Species 



Days 

required 

to double 

weight 



100 x>arts by weight of milk 
contains in grams 



Protein 



Ash 



Lime 



Phos- 
phoric 
acid 



Man . . 

Horse . 
Cow . . 
Goat. . 
Sheep . 
Pig . . . 
Cat . . . 
Dog .. 
Rabbit 



180 
(10 
47 
22 
15 
14 

9 

() 



1.6 
2.0 
3.5 
8.7 
4.9 
5.2 
7.0 
7.4 
14.4 



0.2 

0.4 

0.7 

0.78 

0.84 

0.80 

1.02 

1.33 

2.50 



0.03 
0.12 
0.16 
0.20 
0.25 
0.25 



0.45 
0.89 



0.05 
0.13 
0.20 
0.28 
0.29 
0.31 



0.51 
0.99 



Milk and Its Products. 



269 



The composition of the milk of a single species is by no means 
similar to that of another, although the constituents forming it, 
so far as they have been investigated, are of a similar nature. 

The constituents of milk may be divided into the following 
classes: water, fats, proteins, sugar and ash. The water of 
milk constitutes from 85 to 88 per cent and needs no discussion. 

Fats of milk. The fats resemble in chemical constitution the 
animal and vegetable oils and fats already discussed; that is, 




The milk chambers or alveoli of an udder; A and B, secreting alveoli; 
C and D. non-secreting alveoli; E, alveolus, which has discharged 
its milk (cells appear flattened). 

they consist of compounds of fatty acids and glycerine. They 
differ from animal fats chiefly in containing acid radicals of low 
molecular weight, in addition to the heavy acids, such as oleic, 
stearic, and palmitic, which are the principal fatty acids in the 
fats of animal tissue. Butter fat consists of the glycerides of 
at least 9 fatty acids. The lowest member of the group is butyric 
acid, the highest is stearic acid. Oleic acid belongs to another 



270 



Agricultural Chemistry. 



1 



series. The average percentage composition of milk fat is about 
as follows: — 



Per cent 

Butyrin 3.85 

Caproin 3.60 

Caprylin 0.55 

Caprin 1.90 

Laurin 7.40 



Per cent 

Myri.stin 20 . 20 

Palmitin 25.70 

Stearin 1.80 

Olein 35.0 



The properties of these fats are variable, but the important 
fact to notice is the occurrence in milk fat of the first three or 
four fats in the above list, but mere traces of which are present 
in other animal fats. Olein and the first four members of the 
above list are liquid fats ; the others are solid, stearin being the 
hardest. About 8.0 per cent of the fatty acids, chiefly consisting 
of the first three in the series, are soluble in water. The soluble 
acids have a low boiling point and can be separated from the other 
fatty acids by distillation. These facts serve to distinguish butter 
fat from animal fats such as tallow, which contains but traces of 
soluble and volatile fatty acids. INIilk fat, however, varies con- 
siderably both in composition and physical properties, being 
affected somewhat by feed, period of lactation and other circum- 
stances under which the cows are kept. 

Fat exists in milk in the form of minute globules, varying in 
diameter from .0016 to .010 m. m. In the milk of Jersey and 
Guernsey cows the average size of the globules is considerably 
larger than in Holstein milk ; also in the milk of recently calved 
cows the globules are larger than in that of cows far advanced in 
lactation. This fact has an important practical bearing upon 
the speed with which cream rises. The milk of the Jerseys and 
Guernseys throws up its cream very rapidly, while from the milk 
of the Holstein and Ayrshire breeds the cream rises relatively 
slower. 

The proteins. The two most important proteins of milk are 
casein and albumin. Traces of others are present, but they are 



Milk mid Its Products. 27 1 

in such relatively small quantities that they will not be dis- 
cussed here. 

Casein is the chief protein of milk and exists there in a col- 
loidal state and not in perfect solution. It can be separated from 
the milk by the addition of an acid or by the action of the enzyme, 
rennin, which is contained in rennet. In the souring of milk, 
during which process acid is developed, the casein is precipitated. 
The casein formed in this way probably consists of calcium-free 
casein, for it is generally held that casein exists in milk in com- 
bination with calcium. With rennin, however, the calcium-casein 
is split into two compounds, para-casein and whey protein. The 
para-casein in the presence of the soluble calcium salts of the 
milk precipitates out, while the whey protein remains in solution. 
In the absence of calcium salts rennin will not curdle milk. This 
enzyme acts best at 35° C. and is destroyed at 70° C. It is found 
in the stomachs of all mammals, while enzymes possessing similar 
properties have also been found in birds, fishes, many plants, and 
in the products formed by the action of certain bacteria. 

Mere boiling of milk, unless continued for a considerable time, 
does not coagulate the casein. Casein is the only protein of 
cow's milk which contains phosphorus in its molecule. 

Milk albumin differs in some of its physical properties from 
blood albumin. It is in complete solution in milk but coagulates 
and precipitates when heated to 72° C. It is not coagulated by 
rennin or by most acids. It differs from casein in composition 
and contains about twice as much sulphur and no phosphorus. 
In colostrum milk, albumin largely predominates, so that the 
milk coagulates on heating. 

Milk sugar. The sugar contained in milk is known as lactose. 
It occurs in the milk of all animals, but is not present in plants, 
and consequently does not exist in the food of the dairy cow. 
It is prepared by evaporating the whey, left after cheese making, 
to a small bulk, from which lactose will crystallize out in large 
crystals. It possesses a faint sw^eet taste, about one-tenth that 



272 Agricultural Chemistry. 



1 



of cane sugar. By the action of dilute acids or an enzyme known 
as lactase, it is split into a mixture of dextrose and galactose. 

Milk sugar does not readily undergo alcoholic fermentation, 
but is readily changed into lactic acid by certain micro-organ- 
isms. This change in the milk sugar is the cause of milk souring. 
The necessary lactic organisms are very abundant everywhere, 
especially in the vicinity of dairies and barns, and as they 
)nultiply in the milk, more and more lactic acid is formed. Sweet 
milk has an acidity of from 0.12 to 0.20 per cent, expressed as 
lactic acid. When about 0.40 per cent is present, the milk ac- 
quires a sour taste, and when the amount reaches 0.6 to 0.7 per 
cent, curdling commences. "With certain organisms, the amount 
of lactic acid may reach from 2.0 to 3.0 per cent, but ordinarily 
it does not exceed 0.9 per cent. 

The ash of milk. When water is removed from milk by evap- 
oration and the residue then burned, a white ash is always left 
behind. This consists of the mineral matter and salts of the 
milk, together with sulphates, phosphates and carbonates pro- 
duced by the burning of the organic matter of the milk. It 
amounts in cow's milk to about 0.7 per cent, and consists of: — 

Per cent 

Ferric oxide traces to 0.2 

Sulphur trioxide 3.8 to 4.4 

Phosphoric acid 22 to 27 

Chlorine 1^! to Irt 



Per cent 

Potash 22 to 27 

8oda 10 to 12 

Lime 10 to 24 

Magnesia 1 . 8 to 3 



Milk also contains traces of citric acid. This is not free, but 
in combination with bases as citrates and amounts to about 0.1 
]>er cent of the milk. 

The gases of fresh milk are chiefly carbon dioxide, oxj^gen and 
nitrogen. These amount to about 85 c. c. per liter, the carbon 
dioxide constituting approximately 90 per cent of the total gas. 
On standing, or even during the process of milking, there is a 
rapid exchange of gases, the carbon dioxide greatly dimini.shing. 
wliile tbo oxygen and nitrogen rapidly increase. This increase 



Milk and Its Products. 273 

in oxygen and nitrogen is really an absorption of air and em- 
phasizes the necessity of maintaining a pure, sweet atmosphere, 
to which fresh milk is to be exposed. 

Physical properties. Milk is a white, or yellowish white, 
opaque fluid, with a sweet taste. The specific gravity varies 
usually from 1.027 to 1.034. The solids other than fat tend to 
raise the specific gravity, while the fat tends to lower it. As 
cream may be removed and water added without altering the 
specific gravity, no safe conclusion as to the quality of the milk 
can be based on this test alone. When fresh milk is quickly 
cooled and its specific gravity taken at once, and then again after 
some hours and at the same temperature, a small but decided 
rise in density is observable, usually amounting to about 0.0005. 
This is known as Rechnagel's phenomenon, and has been ex- 
plained in several ways. It has been ascribed to the escape of 
gases from the milk ; to a change in the mechanical condition of 
the casein; and lastly to the solidification of the fat globules. 
It is suggested that quick cooling does not immediately solidify 
the fat globules, which are liquid at the temperature of the cow. 
but that they remain in a super-cooled liquid state. As they 
slowly solidify, they contract, thereby increasing the density and 
raising the specific gravity. 

Chemical composition. This varies considerably according 
to breed, individuality, age, period of lactation and food. The 
mean composition, according to many American analyses, is 
as follows : — 



Per cent 

Water 87.1 

Fat 3.9 

Sugar 5.1 



Per cent 

Casein 2.5 

Albumin 0.7 

Ash 0.7 



It must be remembered that these figures, being averages, im- 
ply the existence of many values either above or below those 
given. As a rule the fat is most liable to variation. The fac- 
tors influencing the composition of milk will be briefly discussed 
under the following heads: — 



274 



Agricultural Chemistry. 



Breed, It is well known that breed is a very important factor 
in influencing the composition of milk. The following? table 
gives the average composition of the milk from several individ- 
uals of the breed represented. Individual variations from the 
figures given are of course to be found, and the figures only 
represent the general trend of the breed. 



Composition of Milk of Different Breeds. 



Name of breed 



Solids 



Fat 



I 
Casein 1 Albumin 



Holstein . 
Ayrshire . 
Shorthorn 
Devon . . . 
Guernsey . 
Jersey 



Per cent 
11.80 
12.75 
14.30 
14.50 
14.90 
15.40 



Per cent 
8.20 
3.70 

4.28 
4.89 
5.38 
5.78 



Per rent 
2.20 
2.46 
2.79 
3.10 
2.91 
3.03 



Per cent 
.04 
.61 
.64 
.83 
.65 
.65 



Individuality. It is uncommon to find in a herd of cows of 
the same breed any two individuals whose milk is of the same 
composition. This is true whether we consider single milkings 
or the average of many. 

Age. So far as there are published data on the influence of 
the age of cow\s on the composition of milk, they indicate a ten- 
dency for the heifer to show a slightly higher fat content than 
the mature cow. Individual exceptions, however, are not in- 
frequent, and more data are needed to settle the question. 

Period of lactation. Innnediately after calving, the first pro- 
duct of the udder is colostrum. This is a yellow liquid, of strong, 
pungent taste, and very difl'erent from normal milk. It is 
characterized by containing small clusters of cells, known as 
''eolostnuu granules" and is veiy rich in albumin. This may 
reach 13.5 per cent. Because of the high content of albumin, 
colostrum milk sets to a solid mass on heating. This test serves 
to distinguish it from normal milk. This first milk is exceed- 
ingly impoi'tant to the young animal at birth, and sennas to 



I 



Milk and Its Products. 



275 



cleanse the alimentary tract and properly start the work of di- 
gestion. After eight or ten days from calving the secretion be- 
comes like normal milk, but the colostrum cells can usually be 
foimd in the milk for about 14 days after calving. 

The milk during the first month after calving is generally rich 
in fat and total solids, and these diminish during the second 
month. After the second or third month, the fat and protein, 
as well as the sugar, continue to increase from month to month 
during the entire period of lactation. The following table, taken 
from the data of the New York State Station, represents the 
monthly averages of nearly 100 different lactation periods. 

Influence of Lactation on the Composition of Milk. 



Month of lactation 


Fat 


Proteins 


Casein 


Albumin 


1 


Per cent 
4 30 
4.11 
4.21 

4.25 
4.38 
4.53 
4.57 
4.59 
4.67 
4.90 
5.07 


Per cent 
3.16 
2.99 
3.04 
3.13 
3.25 
3.36 
3.10 
3.47 
3.57 
3.79 
4.04 


Per cent 
2.54 
2.42 
2.46 
2.52 
2.61 
2.68 
2.74 
2.80 
2.90 
3.01 
3.13 


Per cent 
62 


9 


0.57 


3 


0.58 


4 

5 


0.61 
0.64 


s 


0.65 
0.66 
. t>7 


9 


67 


10 

11 


0.78 
0.91 



Occasionally individuals may depart from the general ten- 
dency shown in the above table, but usually they conform to the 
general rule which the table indicates. The average size of the 
fat globules diminishes with advancing lactation, but their num- 
ber per unit volume increases. 

Feed. The influence of the feed of cows upon the composition 
of their milk is a matter upon which many varied opinions are 
held. There is a widespread belief that this influence is con- 
siderable, but all experimental evidence shows it to be very small. 
Under scanty food supply the quality and especially the quantity 



276 Agricultural Chemistry. 

of milk may be considerably reduced. This is evidenced by the 
results secured at the Cornell Station with a poorly fed herd and 
again when the same herd Avas liberallj^ fed. Under those con- 
ditions, where a liberal supply of nutrients was given, the flow 
of milk was nearly doubled and the percentage of fat slightly 
increased. Again, there appears to be some distinct evidence 
that a change from a ration with a Made nutritive ratio to one 
with a narrow ratio, is for a time, attended with a production 
of milk slightly richer in fat; but the change is only transient, 
and even if the food with a high protein ration be continued, the 
milk, after allowance is made for the effect of advancing lacta- 
tion, shows a tendency to return to its previous composition. 

In any case, it appears that, provided cows are sufficiently fed. 
change of feed has very little permanent effect upon the com- 
position of their milk. Violent and sudden changes in the char- 
acter of their feed may cause a sudden fluctuation in the com- 
position of the milk, but after a short period it will tend to re- 
turn to a composition characteristic for that animal. 

The opinion that it is possible to feed fat into milk has mdely 
prevailed, but such a notion is based upon a misconception of 
liow milk is formed. When, however, we remember that the 
cells of the mammaiy gland are selective in function, and that 
with the same feeds a Jersey cow always makes Jersey milk, and 
a Holstein cow Holstein milk, then the many failures to feed fat 
into milk become intelligible. The careful and well planned 
work of Lindsey. in which a number of vegetable oils have been 
added to a basal ration, gave in some cases slight but only tem- 
porary increases of fat in the milk, while with other oils no 
increase whatever was noticed. 

Certain feeds, however, affect the character of the fat in the 
milk, which is manifested by a change in the hardness and phys- 
ical properties of the butter produced. It is agreed that cotton- 
seed meal has the effect of raising the melting point of butter, 
while gluten feed, rich in oil. produces a softer butter of lower 
molting point. In experiments at the Wisconsin Station, long 



II 



Milk and Its Products. 277 

continued feeding of nutrients entirely from the corn plant, as 
well as from the wheat plant, tended to produce soft, low-melting 
milk fats, while the nutrients from the oat plant produced fats 
making a hard butter, with a high melting point. 

Season. The influence of season upon the composition of milk, 
apart from the effect of advancing lactation, is largely associated 
with the food supply. When this is normally maintained and 
the animals are protected from the effect of weather changes, 
variations in the composition of the milk appear to be slight. 

Time and intervals between milking. Where the time be- 
tween milkings is the same and there are no other disturbing in- 
fluences, the composition of morning's and evening's milk shows 
practically no difference. Where the intervals are unequa], 
there may be a considerable variation in the two milkings. In 
an experiment where 17 Shorthorn cows were milked at 6 a. ni. 
and 3 p. m. the average per cent of fat in the morning's milk was 
3.2, and 4.5 per cent in the evening's milk. 

It is well known that the first milk drawn from the udder at 
milking time is very low in fat, sometimes being as low as 1 per 
cent, while the last portion may contain as high as 10 per cent. 
In these two fractions, however, the other constituents are in 
about the same proportion as would be found in the entire milk- 
ing. 

Milk of other animals. The following table compiled from 
sevei'al sources, gives the average composition of the milk of 
other animals; some of the results are probably not truly rep- 
resentative, due to improper sampling. 

There is a considerable difference in the behavior of the casein 
of the milk of different animals when treated with rennet. With 
cow's milk the enzyme of rennet, rennin, gives a coherent, curdy 
precipitate, while with human milk the coagulum is much more 
finely divided. To this fact has been attributed, in part, the 
non-adaptability of cow's milk to infant feeding. It will also 
be noticed that cow's miU? differs from the natural food of the 
human infant in containing more ash and proteins and much less 



278 



Agricultural Chemistry. 



sugar. It is upon these chemical facts that the modification of 
cow's milk, by dilution and addition of lactose, rendering it suit- 
able for infant feeding, is based. However, experience is teach- 
ing that in most cases the whole milk of the cow, without dilution, 
can be safely used for infant feeding. There is a growing be- 
lief, though, that it must not be too rich in fat. 

Preservation of milk. Normal milk as it occurs in the cow's 
udder usually contains relatively few organisms; but in the 

Composition of Milks. 



Animal 



Fat 


Casein 


Sugar 


Per rent 


Per cent 


Per cent 


3.3 


1.5 


6.8 


1.0 


1.1 


5.5 


6.5 


4.3 


5.(1 


5.3 


7.1 


4.2 


1.7 


2.2 


6.0 


4.6 


7.2 


3.1 


2.1) 


3.8 


0. 1 


4.5 


Trace 


4.4 


9.6 


9.9 


3.2 


3.3 


9.5 


4.9 


10.5 


15.5 


2.0 


19.6 


3.1 


S.8 


48.5 


11.2 


1 . : 5 


43.7 


7.1 






Solids 
not fat 



Woman 

Ass 

Goat 

Ewe 

Mare 

Sow 

Camel 

Hippopotamus 

Bitch 

Cat 

Rabbit 

Elephant 

Porpoise 

Whale 



Per cent 
0.2 
0.4 
0.7 
0.8 
0.4 
O.S 
0.6 
0.1 
1.3 
1.0 
2.5 
0.6 
0.5 
0.4 



Per cent 

8.5 

7.8 
10.2 
12.4 

S.6 
I 1.4 
10.2 

4.5 
13.8 
15.0 
20.1 
12.6 
13.1 



operation of milking and during subsequent exposure to the air. 
bacteria, molds and yeasts find admission. They may find their 
way into the milk from the hands of the milker, the teats and 
hair of the cow, and often from the vessel in which the milk is 
collected. The ordinary souring of milk is produced by variou- 
species of bacteria, which during their growth convert the milk- 
sugar into lactic acid. This formation of acid induces the curd- 
ling of the milk. This generally occurs when the amount of acid 
reaches about 0.7 per cent. Curdling is produced by less acid 
if the milk is heated. 

Other organisms, and often of a moie dangerous character. 



Milk and Its Products. 2Y9 

sometimes find their way into milk. Outbreaks of diarrhoea, ty- 
phoid and cholera have been traced to contaminated milk. It has 
also been shown that milk can act as a carrier of tuberculosis. 
Milk, too, has the property of absorbing gases and vapors and in 
consequence readilj' acquires odors and flavors from the air. 

All these facts emphasize the necessity of cleanliness in milk 
production and precautionary measures to check bacterial devel- 
opment should the milk become seeded. Their growth can be 
checked by cooling the milk as soon as it is produced. This pre- 
vents a rapid development of the organisms already in the milk, 
but will not entirely prevent their development. It will prolong 
the sweetness of the milk. In order to destroy the organisms 
which have gained access to the milk, heating or the use of anti- 
septics must be resorted to. Where the process of heating is 
carried on at a temperature high enough to completely destroy 
all organisms and their spores — a process known as sterilization 
and requiring a temperature above 100° C. — undesirable chem- 
ical changes are produced in the milk. The sugar is turned 
brown, the albumin partly precipitated, and the mill? acquires a 
burnt or cooked flavor. To avoid these disadvantages the process 
known as Pasteurization is often substituted. The milk is heated 
to only 60 to 80° C, whereby the flavor is little affected and most 
of the active bacteria are killed. The keeping qualities are thus 
materially increased. 

Antiseptics. By adding various substances to milk, the 
growth of micro-organisms can be impeded, if not entirely pre- 
vented. When, however, such quantities of an antiseptic are 
added as will prevent bacterial growth, then there is little doubt 
that the milk is made unsuitable for human consumption. The 
chief preservatives in common use are boric acid, salicylic acid, 
formaldehyde and benzoic acid. Their use in any quantity is 
reprehensible, allowing uncleanly methods in milk production to 
be practiced, as well as endangering the health of the consumer, 
and should be absolutely prevented. 



280 Agricultural Chemistry. 

Products derived from milk. Cream. The fat of milk exists 
in globules and is specifically lighter than the aqueous portion of 
the milk. This makes the globules tend to rise to the surface, 
where they form a layer of cream. The specific gravity of fat 
at 15° C. is .930, while the serum in which the globules float has 
a specific gravity of about 1.036. The globules are of various 
sizes. They are considerably larger in the milk of the Jersey and 
Guernsey breeds than in the Ayrshire and Holstein breeds. The 
Devons and Shorthorns hold an intermediate position. The 
smaller the globule, the larger is its surface in proportion to its 
volume, and the greater the resistance to its rise. For this reason 
Jersey milk creams easier than that from breeds with smaller 
globules. 

Cream can be separated from milk by gravitation or by sub- 
stituting for gravity the much greater force produced by rapid 
rotation. "When niilk leaves the cow it will have a temperature 
of about 90° F., and where set for cream should be cooled as 
quickly as possible. There are two methods in use for the separ- 
ation of cream by the gravity processes, namely, shallow settiyig 
and deep setting. In the former the milk is placed in shallow 
vessels to a depth of 2 to 4 inches, cooled to about 60° F. and 
kept at that temperature for 24 or 36 hours. The cream layer 
is then removed by a shallow spoonlike vessel, or sometimes by 
running off the milk into another vessel through a hole at the 
bottom of the creaming pan. Under these conditions of cream- 
ing a large surface is exposed, the milk may receive a great num- 
ber of bacteria, and decomposition of a part of the protein and 
sugar may rapidly take place. The cream obtained in this way 
is liable to be contaminated with various strongly flavored pro- 
ducts of decomposition, resulting in a poor quality of butter. 
The process is not efficient, as only about 80 per cent of the milk 
fat is removed. 

By the deep-setting system, the milk, while still warm, is 
placed in cylindrical vessels, usually about 8 to 12 inches in 



Milk and Its Products. 281 

diameter and 15 to 20 inches deep, which are then immersed in 
ice-cold water. The cream rises quickly and the process will be 
practically complete in 12 hours. By this process 90 to 95 per 
cent of the fat can be removed, dependent upon conditions of 
cooling, manipulation, and the breed of the cow. It has been 
found that by this process twice as much fat remains in the skim 
milk from Holstein cows as in that from Guernseys and Jerseys, 
owing to the slower rising of the small fat globules in Holstein 
milk. 

Many explanations of the efficiency of this system have been 
attempted. Since fat expands and contracts with changes of 
temperature more rapidly than does water, the effect of cooling 
upon milk would be to lessen the difference in specific gravity 
between fat and water ; it would also increase the viscosity of the 
milk, both conditions working against a rapid rise of the fat 
globules. Perhaps the most satisfactory explanation is the one 
given by Doctor Babcock. There exists in milk a substance sim- 
ilar in character to blood fibrin, which, when formed produced 
more or less of a network throughout the body of the milk. By 
rapidly cooling the milk, the formation of fibrin threads is 
checked. This allows the fat globules a free path of movement, 
with the resultant rapid formation of the cream layer. The ex- 
istence of fibrin in milk has been definitely proven. 

Separators. A third plan of separating cream is by subject- 
ing the milk to extremely rapid horizontal revolution in a cen- 
trifugal machine. Under this condition the serum, being the 
constituent of heaviest specific gravity, is thrown to the outer 
side of the revolving vessel while the fat globules rise into the 
center of the mass. The milk should be warmed to about 85° F. 
previous to separating, for the purpose of lowering its viscosity. 
By providing suitable outlets, the skim milk can be directed into 
one channel and the cream into another. By adjusting the size 
of one of these openings, thick or thin cream can be obtained at 
will. Both the cream and skim milk thus obtained, are, of course, 
perfectly sweet. The separation of the fat is far more complete 



282 AciricuUural Chemistry. 

than by either of the other processes, from 97 to 98 per cent 
being recovered in a good machine. 

Composition. Cream varies enormously in composition, the 
proportion of fat varying from as low as 10 per cent to as high 
as 60 or 70 per cent. By shallow setting, a product containing 
Irom 15 to 40 per cent is usually obtained; at low temperatures 
about 20 per cent of fat is usually present. In the deep-setting 
process the cream obtained will contain about 20 to 25 per cent 
of fat. Cream separated by the centrifugal process will vary 
according to the mode of working. It may be quite poor, or it 
may contain 50 to 60 per cent. Generally speaking, thin cream 
will contain 35 to 25 per cent of fat, and thick cream 30 to 50 
per cent of fat. 

Devonshire-" clotted cream" is prepared by setting the milk 
in shallow pans and at a fairly cool temperature for 12 hours. 
It is then heated to a temperature of 70 to 80° C. until the surface 
becomes sharply wrinkled. It is then set in the cold for 12 hours 
and skinnned. Such clotted cream usually contains about 58 
per cent of fat, 34 per cent of v»ater and about 8 per cent of 
solids not fat. 

Skimmed milk varies in com])()sition according to the more or 
less complete removal of the fat. IMilk thoroughly skimmed 
after shallow setting will contain about 1 per cent of fat. "With 
deep setting and ice. the per cent of fat left in the milk will vary 
from 0.15 to 0.40. When the centrifugal machine has been used 
the percenta^ge will be from .05 to .15. ]\Iilk of average quality 
may be expected to yield with a good centrifugal machine, skim- 
med milk of about the following composition : — 



Per cent 

Casein .3.11 

Albumin 0.42 

Ash, etc 0.8W 



Per cent 

Water 90.54 

Fat 0.10 

Sugar 4.94 

Skinmied milk contains a valuable amount of food stuffs, and 
should be utilized on the farm for feeding pigs or in other ways. 
Though poorer in fat. machine separated milk has the advantage 



Milk and Its Products. 283 

of being sweet and of keeping better than the product from other 
processes of skimming. 

Butter. AVhen cream or milk is agitated for some time, the 
fat globules coalesce and butter separates out in irregular masses. 
While these masses are not continuous fat, very few of the 
original globules remain. The spherical globules visible in but- 
ter luider the microscope consist of minute drops of butter-milk 
or water, enclosed in the fat. 

Churning is a mechanical process. The fat globules collide, 
adhere, and the large irregular masses thus formed become cen- 
ters of growth, to which other fat globules adhere. Portions of 
the aqueous liquid, butter-milk, are enclosed in the masses of fat. 
During the "working" of the butter, the butter-milk is partly- 
pressed out. For butter to be of good quality, it must possess 
a certain texture and grain and be neither hard nor grea.sy. This 
desirable result can only be attained by careful churning at a 
favorable temperature. If the temperature of the cream is too 
low the butter will be long in coming and will be hard in texture. 
If the temperature is too high, the butter will come very speed- 
ily, but the product will be greasy and destitute of grain. No 
temperature can be fixed as the best at which churning should 
always take place. The proportion of solid and liquid fats in 
the milk varies somewhat with the breed and feed of the cow. 
and this necessitates a change in the temperature. From 45 to 
B5° F. is the greatest range usually employed and in most cases 
from 50 to 60° F. is chosen. "Ripened" or sour cream must 
be churned at a higher temperature than that required for sweet 
cream. The exact temperature most suitable for churning may 
be ascertained, by recording every day the temperature employed, 
the length of time occupied in churning and the character of the 
product. "When this is done the experience gained can be used 
in selecting the most suitable temperature. 

The temperature may idse during churning, work being eon- 
verted into heat. This causes an expansion of the air in the 
chum. In addition, the carbon-dioxide in solution in the serum 



284 Agricultural Chemistry. 



I 



of a ripened cream is driven out by the agitation. These two 
factors give rise to the pressure observed within the chum. 
Churning should always be stopped as soon as the butter appears 
in fine grains. This allows a more complete separation, by wash- 
ing, of the butter-milk, and removes one of the important factors 
in the production of mottles in butter. Further, the more com- 
pletely the butter-milk is removed, the better will be the keeping 
((ualities of the butter. 

Freshly separated cream is sometimes churned, but it is gen- 
erally admitted that the best flavor and aroma for butter can 
only be obtained by the use of properly ripened cream. This is, 
cream to which lactic acid organisms have either gained access 
spontaneously, or, as is preferred in modem practice, have been 
added in the form of a "starter" of sour skimmed milk or some 
pure culture of the lactic organisms. The degree of ripeness 
which is probably best, corresponds to about 0.5 per cent of lactic 
acid ; but the acidity most suitable depends to some extent upon 
the flavor desired in the butter. If the cream is over ripe, the 
casein present may be hardened and on churning is found as 
white specks or flakes in the butter, spoiling its appearance and 
endangering its keeping qualities. 

Salt is usually added to butter, serving both as a condiment 
and as a preservative, the proportion varying from a mere trace 
to 5 or 6 per cent. 

Composition of butter. The main constituent is of course 
fat, but in addition, water, casein, milk sugar and ash are also 
present. The amount of fat is usually about 80 to 86 per cent, 
water about 11 to 12, casein from 0.6 to 1.5 and salt from 0.1 
to 4.0 per cent. Under the present pure food law of the United 
States it is unlawful to sell butter containing more than 16 
per cent of water. So called "milk-blended butters" prepared 
by kneading butter in milk, usually contain an excessive quantity 
of wntcr and a high proportion of casein. 

Renovated butter. In this country old and rancid butter is 
sometimes converted into what is kno\\Ti as "renovated," "pro- 



Milk and Its Products. 285 

cess, " or " aerated ' ' butter. This is done by melting the butter, 
separating the fat from the casein, water, etc., blowing air 
through the fat to remove the unpleasant odors, and then churn- 
ing the liquid fat with milk until an emulsion is formed. This 
is then quickly cooled in ice and a granular mass results. It is 
then worked, salted, and made up as butter. 

Oleomargarine is also known as ' ' margarine " or ' ' butterine. ' ' 
This product, which is intended as a substitute for butter, is 
made by churning so called ''oleo oil" with lard, milk, sometimes 
a little butter, and occasionally cotton-seed oil or peanut oil, in 
a warm state. After the churning the mixture is quickly cooled, 
salted and "worked." Where coloring matters are used, with 
the intention of imitating butter, a tax of 10 cents a pound is 
imposed. On uncolored "oleo" a tax of 1/2 cent per pound is 
levied. 

The "oleo oil" is made from beef fat by melting, carefully 
clarifying, and allowing it to stand at a temperature of about 
30° C. The semi-solid mass which results is then separated by 
a press into solid stearin and a liquid composed of olein and 
palmitin. 

Pure butter can be distinguished from "renovated" butter 
and from "oleo" by its behavior when heated in a test tube or 
spoon over a flame. Oleomargarine and renovated butter boil 
with much sputtering and produce no foam, or very little, while 
genuine butter in boiling produces more foam and less noise. 

Butter-milk. The liquid remaining in the chum after the 
separation of butter from the cream varies a good deal in com- 
position. With good churning of ripened cream, the percentage 
of fat in the butter-milk may be 0.3 or less. When sweet cream 
is churned 1.0 per cent of fat may be expected. The average 
composition of butter-milk will be about as follows: — Water, 
90.9 per cent ; proteins, 3.5 ; fat, 0.5 ; sugar and lactic acid, 4.4 ; 
ash, 0.7. The chief use for butter-milk has been as food for pigs, 
but there is a growing demand for it as human food. The finely 



286 



A fj r ic iiltura I Cli e m is try . 



I 



divided condition of its protein makes it readily and easily di- 
gestible. The preparation of a new product, butter-milk cream, 
will probably increase the consumption of this material as human 
food. This product is prepared by holding the butter-milk at 75 
to 78° F. for about 2 hours, and finally heating to 130 to 140° F. 
for a short time. This treatment induces an aggregation of the 
finely divided protein, allowing the material to be strained and 
collected, which otherwise could not be done. 

The following table shows how the various constituents of 100 
pounds of milk are distributed when the milk is creamed and 
made into butter: — ' 

Distribution of Milk Solids in Butter Making. 





Products from 100 lbs. of milk, in lbs. 




100 lbs. 
of milk 


20 lbs. 
of cream 


S«--^ Butter 


Batter 
milk 


Total solids 

Fat 


13.00 
4.00 
3.50 
4.75 
0.75 


5.18 
3.88 
0.50 
0.75 
0.05 


7.82 
0.12 
3.00 
4.00 
0.70 


4.00 
3.83 
0.10 
0.05 


I.IS 
05 


Casein and albumin 

Sugar and acid 

Ash 


0.40 
0.70 
03 









The 4 pounds of solid matter recovered in the butter, which 
contains 3.83 pounds of fat, together with the salt and water 
present, make about 4.6 pounds of marketable butter. 

Condensed milk and milk powders. Condensed milk is pre- 
pared by evaporating milk in vacuum pans until its volume is 
reduced to about one-third or one-fourth of the original, and 
then sealing the condensed product while hot. In many brands 
cane sugar is added in large proportion. This aids in preserving 
the product, even after the cans are opened. To other brands, 
often known as "evaporated cream," no sugar is added. 

The composition of these products varies, the fat being liable 



Mill- and Ih Products. . 287 

to considerable variation. The following analysis may be taken 

as typical : — 

Sweetened Unsweetened 

Per cent Per cent 

Water 25.7 71.7 

Fat 10.7 8.1 

Protein 8.5 8.7 

Milk sugar 11.9 9.9 

Cane sugar 41.9 

Ash 1.:^ 1-6 

Milk powders are made by several processes. One of the 
earliest was to evaporate the milk in a thin layer, on a heated 
revolving drum. By this process the evaporation of water takes 
place rapidly and the dried film of milk drops, or is scraped, 
from the rolls, appearing as a thin yellow scale. Another proc- 
ess, of recent date, consists of atomizing the milk under pressure 
into a moving volume of warm dry air. The moisture is in- 
stantaneously absorbed and by the use of centrifugal force, the 
vapor charged air is made to give up the minute particles of 
suspended matter. The product is a fine flour, possessing, in 
common, with some other brands prepared by other methods, 
the properties of milk when again stirred up in water. There 
are preparations on the market which do not have these prop- 
erties, probably because they have been subjected to too high 
heat in the drying process. 

Of the several milk powders examined by the authors, only 
one contained any appreciable quantity of fat. It appears that 
most, if not all of these powders are prepared from skimmed, or 
partially skimmed milk. This .is probably necessary, in order 
that dessication may be more complete and the keeping qualities 
of the product well insured. One product examined, and rep- 
resented as a preparation from whole milk, contained but 9 per 
cent of fat. A milk powder prepared from average whole milk 
should contain at least 25 per cent of fat. 

Various other dry foods are prepared from the casein of milk, 



288 Agricultural Chemistry. 



among which are "plasmon" and "nutrose." "Plasmon" is 
made by treating the curd of skimmed milk with sodium bi- 
carbonate and drying the thoroughly mixed product in an at- 
mosphere of carbon-dioxide. "Nutrose" is also a sodium com- 
pound of casein. 

Cheese. The principal varieties of commercial cheese are pre- 
pared from milk by the action of rennet. Rennet is made by 
extracting the fourth stomach of the calf with a 5 to 10 per cent 
solution of common salt. Its power to coagulate milk is due to 
the presence of an enzyme called rennin, which plays a similar 
part in the process of digesting milk in the calf's stomach. Ren- 
nin coagulates the casein of the milk, forming a curd which 
mechanically entangles almost all the fat of the milk, leaving 
the albumin and sugar in the whey. Rennin acts more rapidly 
at about 102 to 104° F. In cold milk it is slow in its action, 
while at temperatures above 120° P. it is retarded, its action en- 
tirely ceasing at 130° F. In milk containing some acid, but not 
enough to curdle it, rennin action is hastened. 

It is impossible in a work of this scope to describe the varieties 
of cheese and their methods of manufacture. 

The common practice followed in the preparation of American 
Cheddar cheese is to "ripen" the milk to an acidity correspond- 
ing to about 0.25 per cent of lactic acid. This is done by adding 
to it a starter consisting of sour milk or a pure culture of lactic 
organisms. The necessary rennet is then added, the milk being 
previously warmed to 82 to 85° F. After the curd is sufficiently 
firm, requiring about 30 minutes, it is cut into cubes and the 
temperature of the vat raised to 100° F. It is maintained at 
that temperature for 1 to 2 hours, during which time the curd 
shrinks and the' acidity increases. After proper acidity is de- 
veloped, the whey is drawn, the curd piled in one end of the vat 
and kept wann. In this condition it mats into a solid mass. It 
is finally passed through a grinding mill, salted, and pressed into 
molds. The cheese is then placed in a curing room at a tem- 
perature of 50 to 60° F. and allowed to ripen, A lower tem- 



1 



Milk and Its Products. 



289 



perature than this can be used, with great improvement in the 
quality of the product. In the manufacture of Swiss cheese the 
milk must be in a sweet condition. No acid is developed and the 
curd is cooked at a temperature of 125 to 130° F. The curd is 
placed in molds and the salting done by surface application. In 
making soft cheese the curd is not cut or pressed, but simply 
allowed to drain on a cloth or frame. 

Reckoning that the fresh cheese which goes into the cheese 
room contains about 36 per cent of water, the products from 100 
lbs. of normal milk will be as follows: — 



Products from 100 Lbs. of Normal Milk. 



Total 
product 


Water 


Protein 


Fat 


Sugar 


Ash 




Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Milk 


100.0 


87.10 


3 40 


3.90 


4.85 


7.5 


Cheese 


10.40 


3.94 


2.57 


3.59 


0.17 


0.13 


Whey 


89.60 


83.16 


0.83 


0.31 


4.68 


0.62 



Ripening. Cheddar cheese ripens quickest at a moderately 
warm temperature, 50 to 60° F. being usually employed. It has 
been shown that it will also ripen at a much lower temperature — 
even at 30"^ F. — and the product will be of excellent quality. The 
time of ripening is necessarily longer when conducted at the 
lower temperature. During this curing process many complex 
changes occur. The sugar is converted to lactic acid, some water 
evaporates, and the insoluble proteins are partly converted into 
water soluble products. Ammonium compounds are also pro- 
duced during the ripening process. Experiments have shown 
that fresh cheddar cheese contains but from 5 to 10 per cent of 
its protein in water soluble form, while at the end of 5 months, 
35 to 40 per cent will be found in that form. These changes, ac- 
cording to one view, are produced primarily by the lactic acid 
organisms. Another theory ascribes them to enzymatic action, 
the enzymes being galadase, which is present in all milks and 



290 



A gricuUural Chemisti'y. 



possesses the power of peptonizing casein, and pepsin, contained 
in the rennet extract used. "Whatever may be the cause of these 
changes, there can be no doubt that during the curing process 
the flavor and aroma are developed and that a considerable por- 
tion of the insoluble nitrogenous bodies are converted into water- 
soluble forms. The fat of cheese undergoes slight change during 
ripening, a small proportion of the neutral fat being decomposed 
and butyric and other fatty acids formed. The sugar which was 
present when the cheese was first made also disappears after a 
period of 7 to 10 days. Lactic acid is the main product formed 
from the sugar, although other products, probably of great im- 
portance to flavor development, are produced. 

The ripening of special kinds of soft cheese, such as Roquefort 
and Camembert is attributed to such special ferments as molds, 
introduced during the process of manufacture. The average 
composition of various cheeses is given in the following table: — 

Composition of Cheese. 



Water 



Protein 



Cheddar . . 
Cheshire . 

Swiss 

Edam 

Roquefort 

Brie 

Limburj^ . 



Per cent 
34.4 
32.(3 
35.8 
36.3 
31.2 
50.4 
35. r, 



Per cent 
20.4 
32.5 
24.4 
24.1 
27. H 
17.2 
28.5 



Fat 



Ash 



Per cent 
32.7 
2(5.0 
37.4 
30.3 
33.2 
25.1 
29.8 



Per cent 
3.6 
4.3 
2.4 
4.9 
6.0 
5.4 
5.9 



Under the United States pure food act, the following defini- 
tions, of cheese were established. 

(1) Whole milk or full cream cheese is cheese made from milk 
from which no portion of the fat has been removed. 

(2) Skim milk cheese is cheese made from milk from which 
any portion of the fat has been removed. 

(3) Cream cheese is cheese made from milk and cream or milk 
containing not less than 6 per cent of fat. 



MilJc and Its Products. 291 

Standard. Whole milk or full cream cheese contains, in the 
water-free substance, not less than 50 per cent of butter fat. 

The term ''full cream" simply means that in the manufacture, 
whole milk has been used. It gives the impression that cream 
has been added, but such is not the case. 

In some cases, cheese is adulterated by the addition of foreign 
fat, as lard. Such cheese is usually known as "filled" cheese. 

Whey. As already stated, whey contains almost all of the 
milk sugar and albumin originally present in the milk, as well 
as a portion of the ash. The amount of fat in the whey will de- 
pend upon the treatment the curd has received. If the milk has 
been rich, the temperature of cooking high, and the curd roughly 
handled, considerable quantities of fat will be present. "Where 
whey is rich in fat, it is customary to recover it for the manu- 
facture of whey butter, either by allowing it to rise by gravity 
or through the use of the separator. The average composition 
of whey is about as follows : Water, 93.3 per cent ; protein, 0.9 : 
fat, 0.3 ; sugar, 4.9 ; ash, 0.6. 

The cheese yield of milk. As has been seen, the two milk con- 
stituents that must determine the yield of cheese are casein and 
fat. The percentage of these varies in milks from different in- 
dividual cows. They are not always in the same relation in two 
different milks. Milks of high fat content are not proportionately 
richer in casein than milks of low fat content. As a rule, for 
100 pounds of fat in Jersey and Guernsey milk, one may expect 
55 to 65 pounds of casein, while in the milk from the Ayrshire 
and Holstein breeds, there will be 65 to 75 pounds. There will 
be individual exceptions to this general statement. 

In herd milks, although the relation of casein to fat is more 
constant, nevertheless variations in the proportion of these two 
constituents exist. The general rule that high fat milks do not 
yield in proportion to their fat, as much cheese as low fat milks, 
finds its explanation in the fact that high fat milks have pro- 
portionately less casein. This is illustrated in the following 



292 



Agricultural Chemistry. 



table, which represents some work done by Babcock at a number 
of Wisconsin cheese factories. 

Relation of Composition of Milk to Cheese Yield, 



No. of 


No. of 


Range 


Average 
per cent 


Average 
yield of 


Lbs. of 
cured cheese 


groups 


reports . 


of fat 


of fat 


cheese per 
100 lbs. milk 


for 1 lb. fat 


1 


24 


Under 3.25 


3.12 


9.19 


2.94 


2 


90 


3.25-3.50 


3.38 


9.28 


2.73 


3 


134 


3.50-3.75 


3.60 


9.40 


2.61 


4 


43 


3.75-4.00 


3.83 


9.80 


2.56 


5 


46 


4 00-4.25 


4.09 


10.30 


2.51 


6 


20 


Over 4.25 


4.44 


10.70 


2.40 



It will be seen that the yield of cheese in proportion to the 
fat is less in the rich milks than in the poorer milks. A milk 
testing 6 per cent of fat will not make twice as much cheese as 
one testing 3 per cent. 

Making out dividends at cheese factories. "While the inequal- 
ity of the cheese-yielding capacity of milks, and of the distribu- 
tion of dividends, based on their fat content alone, has been 
recognized, it has been quite generally asserted that such in- 
equality disappeared because of the improved quality of the 
product made from the milks of higher fat content. This is true 
when we consider cheese made from skimmed or partly skimmed 
milk and from milk very rich in fat or re-inforced with cream. 
But within the range of normal factoiy milk testing in fat from 
3 to 41/2 per cent, the quality of the product, as judged by buyers 
for the market, does not show uniform improvement with increase 
of fat in the milk. This has been shown by tlie work of thf 
Canadian Experiment Station at Guelph and by the Wisconsin 
Station. No grading in the price of cheese, made from normal 
whole milk, based on its fat content, is at present practiced. 
Other factors, as the sanitary condition of the milk from which 
the cheese is made and the suhsequent ripening processes, play 
an important part in determining the quality of the product. 



Milk and Its Products. 293 

Normal factory milks may vary in their cheese-yielding capac- 
ity, and the quality of the product from such milks is not deter- 
mined by those variations that may occur in the fat and casein 
content. It is clear that the most complete and equitable method 
for the distribution of dividends at a cheese factory, is to allow 
for the amounts of both fat and casein delivered by the patron. 

In its simplest form this consists in allowing equal values for 
both the fat and the casein, the amounts of which can be de- 
termined by methods applicable to factory conditions. Such 
tests are the Babcock fat test and the mechanical casein test 
devised by one of the authors. A patron delivering 100 pounds 
of milk, containing 3.5 per cent of fat, and 2.4 per cent of casein, 
should be paid on the basis of 5.9 pounds of cheese solids deliv- 
ered. The price per pound of cheese solids would be determined 
by the price received for the cheese in the market. 



CHAPTER XIII 
INSECTICIDES AND RELATED SUBSTANCES. 

A number of miscellaneous substances used in the agricultural 
industries depend primarily upon their chemical composition for 
effectiveness. Prominent among these substances are various 
preparations for the control or suppression of parasitic pests 
upon plants and animals and the restriction of contagious dis- 
eases. Brief consideration will be given here to the composition 
and action of the more important of these substances. For their 
practical applications, reference shovild be made to special books 
and bulletins on these subjects. 

The following classification of these substances will be followed 
for the sake of order and convenience: — 
I. Insecticides. 
II. Fungicides. 
III. Disinfectants, deodorants and antiseptics. 
IV. Incidental materials. 

Insecticides are substances used for dastruction of insects feed- 
ing upon the fruit, foliage or bark of vegetation and for the re- 
moval of ticks and similar pests from animals. These materials 
have won general recognition as essential factors in the produc- 
tion of high grade fruit. 

They may be classed as stomachic, contact, or gaseous poisons, 
according to their mode of action. Such insects as the codling 
moth of the apple and the "potato bug," which are surface feed- 
ers, may be reached by poisons of the first class; the aphides or 
plant lice and other sucking insects must be attacked by poisons 
of the second class; and the resistant scale insects and other 
pests are most efficiently destroyed by fumigation with a poison- 
ous gas. 

Stomachic poisons for insects are generally dependent upon 
arsenic foi- thoii- poisonous effects. Arsenic does not enter these 



Insecticides and Belated Substances. 295 

substances as the free element, but as a constituent of ''white 
arsenic," technically called "arsenious oxide" or "arsenious 
acid." Soluble compounds of arsenic were at first tested as in- 
secticides, but they were found to cause serious injury to foliage. 
Later experiments have demonstrated that arsenical compounds 
insoluble in water produced the desired effect, probably by virtue 
of the solvent action of the juices of the digestive tract of the 
insect. The resulting effort to furnish the arsenic of insecticides 
in insoluble form has been stimulated also by the passage of state 
laws restricting the amount of arsenic permissible in soluble form. 
Paris green has been a leading insecticide in America for fifty 
years. It was first used, apparently, in an attempt to control 
the Colorado beetle or "potato bug" which had made its ap- 
pearance in the western United States. This stomachic poison 
contains arsenious acid, acetic acid and copper in a definite chem- 
ical structure known as "Schweinfurt's green," and technically 
known as ''copper aceto-arsenite. " It is prepared by adding a 
hot solution of arsenious oxide to a hot solution of copper acetate. 
Paris green separates from the mixture and settles out as a rather 
fine powder of a clear, green color. The pure compound is prac- 
tically insoluble in water, but readily soluble in ammonium hyd- 
loxide. or annnouia water, and has the following composition: 

Pel' cent 

Copper oxide 31 . 29 

Arsenious acid 58.65 

Acetic acid 10.0(> 

Scorching of foliage by applications of Paris green suspended 
in water was frequently observed during its early use. Gillettte 
showed, in 1890, that the use of lime water or Bordeaux mixture 
with Paris green prevented this injury. A year later, Kilgore 
found that the scorching effects were due to soluble forms of 
arsenic and concluded that the preventive substances acted by 
virtue of their lime, which fixed the soluble arsenic in insoluble 
compounds. Experiments at the New York Experiment Station 
with Paris green and sodium arsenite applied to potatoes led to 



20C Agricultural Chemisti-y . 



n 



the conclusions: "That Paris green is not injurious to potato 
foliage if applied in moderate quantity with lime water or Bor- 
deaux mixture evenly distributed;" and "That sodium arsenite 
should not be applied to potatoes except with Bordeaux mix- 
ture." 

Adulteration and the manufacture of impure Paris green were 
more or less prevalent previous to the passage of insecticide laws. 
<jrypsum or sulphate of lime Avas one of the most common adulter- 
ants. This has little if any insecticidal value and was added 
to increase the bulk. Other impurities may result from the use 
of crude materials or careless methods in preparation. Wood- 
worth has given some simple tests to detect common forms of 
adulteration. 

The ammonia test is performed by taking an amount of Paris 
green that can be held on a five cent piece, transferring it to a 
drinking glass and adding about six tablespoonfuls of household 
ammonia or "spirits of hartshorn." Keep the contents of the 
glass well stirred for five minutes. If the "green" is pure, it 
will then form a clear, dark-blue solution and leave no solid 
residue. If gypsum is present, it will form a white suspension 
in the liquid and finally settle to the bottom of the glass. This 
is not a conclusive test since impurities soluble in ammonia may 
be present. 

The glass test often enables one to distinguish adulterated 
samples not detectable by ammonia. Take such an amount of 
Paris green as can be picked up readily on the point of a pen 
knife and place it on a small rectangular piece of clear glass. 
Holding the glass in an inclined position, gently tap the lower 
edge and the Paris green will move down the inclined plane leav- 
ing a track of dust behind. In the case of a pure "green," the 
dust will be of a bright green color. If the sample is impure, 
it may leave a white, pale-green or other-colored streak, depend- 
ing upon the color of the adulterating sub.stance. This test is 
best used for comparing unloiown samples with a sample known 
to be pure. Like the ammonia test, it is not infallible. Varia- 



Insecticides and Belated Substances. 



297 



tions in the color of samples in bulk, especially an abnormally 
pale shade, and a tendency to dampness or lumping, indicate 
almost certain adulteration. 

Microscopic examination offers the most certain and satisfac- 
tory of simple methods for testing the purity of Paris green. 
The sample is prepared for this test as in the "glass test" just 
described and the dust is then examined under a medium power 
objective. The Paris green will be seen in the form of clean 




On the right — pure Paris-green; on the left — adulterated Paris-green. 

round balls ; and in perfectly pure samples these are all that can 
be seen. Impure samples will exhibit also a considerable quan- 
tity of material of crystalline or irregular shapes, and usually 
white in color. Excess of free arsenious oxide is not so readily 
distinguished by this test. "When mixed with the prepared Paris 
green it is as easily recognized by the microscope as is any other 
form of adulterant, but when added in the process of making, 
it adheres firmly to the particles of true green and causes them 
to stick together in clusters. 

Chemical analysis is the only absolute means of determining 
the purity of this insecticide. One of the most important of the 
chemical determinations, is that for estimating the soluble ar- 
senic in Paris green and other insecticides. Two procedures are 



298 .\(/rici(Uiintl Cheinistry. 

in use. In one case the sample is extracted with a hot 33 per cent 
solution of sodium acetate, while in the other ease it is extracted 
for several days with cold water and the amouiit of arsenic in 
solution estimated. The former method apparently shows more 
nearly the amount of soluble arsenic that may be present, Avhile 
the latter treatment more nearly simulates conditions to which 
the insecticide is exposed in the field. 

Control laws have been passed by some states to regulate the 
composition and sale of insecticides as has been done in the case 
of commercial fertilizers and feeding stuffs. In .some cases, spe- 
cial stipulation is made with regard to the amount of free ar- 
senious oxide permissibla in Paris green. Idaho allows a max- 
imum amount of six per cent for this constituent and California 
allows but four per cent. 

Green arsenoid is the trade name for a compound resembling 
Paris green in composition and effects. It contains no acetic 
acid but is formed from copper oxide and arsenious oxide, and 
is technically knoA\Ti as copper arsenite. The pure com]iound 
contains about 53 per cent of arsenious oxide. Sodium sulphate 
or Glauber's salt is a by-product in the process of preparation 
and may occur together with sand and other impurities in such 
an insecticide; tliey should, however, be present in only small 
amounts. The following data from an analysis of green arsenoid 
illustrates the relative ellt'ect of sodium acetate solution and ci^ld 
water upou the jirscuic of insecticidt^s : 

Free argeiUDUs acid Per cent 

(extracted with sodium acetate) 3 23 

(extracted with cold water) 5.88 

This insecticide has given cxct'llent results wlini mixed with 
lime to "bind" the soluble arsenious oxide. 

London purple was imported from England by l-5essey in 187^^ 
as a substitute for Paris green in destroying the potato beetle. 
It is prepared by boiling a purple residue from the dye industry, 
containing free arsenious acid, with slaked lime. Calcium ar- 
senite is formed at first, but by subsequent l)oiling and exposure 



Insecticides and Related Substances. 299 

to the air, this may be partly oxidized to calcium arsenate. This 
insecticide carries some impurities brought over from the dye- 
making process, and as a result of insufficient addition of lime 
or incomplete boiling some of the arsenious acid may be present 
in free condition. Haywood examined four samples with the 

following results: 

Per cent 

Moisture 1.87-4.07 

Sand 2.46-3.55 

Arsenious acid, total 6.40-17.31 

Arsenic acid, total 26.50-35.62 

Arsenious acid, soluble in cold water 1 .44-13.49 

Arsenic acid, soluble in cold water 7. 12-19.56 

Lime 23.59-25.09 

Water decomposes both calcium arsenate and calcium arsenite 
to some extent and consequently a solubility determination with 
water does not show how much arsenious acid was actually free. 
These soluble arsenic salts are probably less objectionable than 
free arsenious acid, although it is recognized that London purple 
is more injurious to foliage than is Paris green and common 
arsenic (arsenious oxide) is more harmful than either. This con- 
dition may be corrected by adding lime to the London purple 
when suspending it in water for application to foliage. Since 
it is subject to considerable variation in composition this insec- 
ticide should be bought on guarantee of purity. 

Calcium arsenite was proposed by Kilgore as an insecticide, 
following his observations with Paris green. This can be made 
by boiling one pound of arsenious oxide and two pounds of lime 
in water and diluting for use. Since this compoimd has been 
shown to form about 75 per cent of London purple, it is probably 
more economical to use the latter insecticide. 

Arsenite of soda is prepared by boiling arsenious oxide with 
four times its weight of sodium carbonate. The injurious effects 
of this compound iTpon potato foliage have been referred to. 
Similar results were produced in trials of sodium arsenate against 
the gypsy moth in Massachusetts. 



300 Agricultural Chemistry. 

"Dips'" which have proved very efficient in destroying sheep 
ticks have given sodium areenite recognition as a valuable in- 
secticide. The following fornmla has b^en used with success : 

Arsenite of aoda 5 poands 

Soft Boap o poand« 

Aloes 12 ooncee 

Water lOrj gallons 

The soap is said to increase the retention of the dip on the 
fleece and aloes renders it distasteful to the animal and prevents 
poisoning. Sodium arsenate has been used against locusts by 
adding it to sugared water and spraying the grass in the infested 
region. 

Lead arsenate was recommended as an insecticide in 1892 and 
was first used against tent caterpillars. It is prepared by adding 
lead acetate to .sodium arsenate in water. These substances dis- 
solve readily in the cold and react to form sodium acetate and 
lead arsenate, the latter remaining suspended as a fine white 
powder. This in.secticide should be handled in the form of a 
paste, for once dried it is suspended with difficulty. Recent ex- 
periments show that lead nitrate is to be preferred to the acetate 
in making the arsenate because the product remains in suspeusion 
better and contains more lead-hydrogen-arsenate. carrying a 
higher percentage of arsenic than Is the case with preparations 
from the acetate. This Ls apparently the most insoluble of all 
the arsenical insecticides and least likely to .scorch the foliage. 
Headden has shown, however, that care should be taken to use 
pure water in the preparation of even this spraying mixture. 
Solutions of 0.1 per cent sodium sulphate or 0.05 per cent com- 
mon .salt dissolve considerable amounts of arsenic from lead ar- 
senate. Practical spraying tests with lead arsenate in di.stilled 
water showed that sodium carbonate or sodium chloride at the 
rate of 10 grains per gallon in the spray fluid produced severe 
injurj- and 40 grains of the latter salt per gallon injured about 
50 per cent of the foliage. Salt waters and alkali .surface water; 
must therefore be avoided. 



Insecticides and Jtelated SvJbstances. 301 

Haywood gives the following directions for preparing lead 
arsenate; for each pound of lead arsenate to be made, use — 

Ounces 

Formula A. .Sodium arsenate (65 per cent ) 8 

Lead acetate (sugar of lead) 22 

Korniula H. Sodium arsenate (65 per cent) 8 

Lead nitrate IB 

Dissolve each salt separately in 1 to 2 gallons of water, using 
wooden vessels. When dissolved, pour the lead solution into the 
sodium arsenate, stirring thoroughly until the mixture just turns 
a potassium-iodide test paper to a bright yellow. The lead salt 
is then in slight excess. A large excess should be avoided. Al- 
low the lead arsenate to settle, and pour off the liquid. These 
chemicals are extremely poisonous and should be plainly labeled 
and handled with care. 

Pink arsenoid is a commercial preparation made by adding 
lead acetate to sodium arsenite and coloring the insoluble product 
with a dye. It is composed chiefly of lead arsenite, only a small 
proportion of the arsenic being soluble, and has given satisfac- 
tory results. 

White arsenoid was the product of an attempt to put barium 
arsenite upon the market as an insecticide. Contrary to expec- 
tation, all the arsenious oxide of this preparation was found to 
be soluble in cold water. It gave poor results and was short- 
lived. 

White arsenic, or the simple arsenious oxide, has been used as 
a constituent of "dips" and various insect and animal poisons. 
It is volatile at a comparatively low heat and mixed with sulphur, 
it has been successfully used against ants by forcing the vapors 
into the nest. 

Arsenical poisoning may occur in the case of trees heavily 
sprayed with arsenical insecticides. Headden found arsenic in 
diseased fruit trees and this condition was correlated with an 
accumulation of arsenic in the soil in compounds from which it 
was rendered gradually soluble by the salts of the soil solution. 



302 Agricultural Chemisti-ij. 

Paige found, in connection with reported poisonings associated 
with combating the gypsy moth, that the amount of lead arsenate 
consumed by herbivora with the grass from beneath sprayed 
trees might lead to serious results. These findings emphasize the 
need of care in the use of poisonous spraying mixtures. 

Hellebore, from the root of the pokeroot plant, and Pyrethrum 
or insect powder, from the flower heads of certain plants, have 
poisonous insecticidal properties attributed to alkaloids. Both 
deteriorate with age. 

Purity and efficiency of insecticides can only be insured by 
purchasing them under guarantee or under recommendations 
from reliable authorities, such as the state experiment stations. 
or by the purchase of simple constituents to be combined by the 
purchaser. 

Contact poisons may act by their caustic properties and by 
absorption from the surface of the insect, or by closing the tra- 
cheae or breathing tubes. These Avill now receive our consid- 
eration. 

Lime-sulphur wash is typical of the former class of insecti- 
cides. It was used in California as a sheep dip, where it was 
fiist api)lied also to the San Jo.se scale in 1886. The wash was 
prepared by boiling sulphur and slaked lime in equal parts, 
which produced first a simple sulphide of lime (CaS) of a white 
color. Prolonged boiling causes the color of the wash to pass 
through shades of yellow to a deep orange color with the forma- 
tion of poly-sulphides of lime carrying increasing proportions of 
sulphur. The chemistry of lime-sulphur wash has been inves- 
tigated at the New York Experiment Station. The chief com- 
pounds were found to be calcium penta-sulphide (CaSr,), calcium 
tetra-sulphide (CaS^) and calcium thiosulphate (CaSoOo). Boil- 
ing converts the last-named compound into calcium sulphite and 
free sulphur, and the calcium sulphite then oxidizes by exposure 
to the air into calcium sulphate. 

The specific gravity of the wash and the amount of calcium 
and sulphur in solution increased with the amount of lime used. 



Insecticides and Related Substances. 303 

The higher amounts of lime produced more calcium tetra-sul- 
phide, while with the smaller amounts, the mixture was more 
nearly penta-sulphide. The largest amount of soluble sulphides 
was formed by boiling about one, hour, especially when the 
largest amount of lime was used. The amount of sediment in- 
(^reased with increased boiling, due to the formation of calcium 
sulphite. It was found that the addition of extra lime to the 
diluted lime-sulphur solution might seriously decrease its in- 
secticidal value as a result of the decomposition of the higher 
sulphides of calcium with formation of free sulphur. Where 
pure lime was used, the sediment, found to consist of calcium sul- 
phite, free sulphiir and hydroxide and carbonate of lime, formed 
suitable material to add in the making of a new wash. It was also 
found that magnesium oxide when present in the lime, as in 
dolomitic limestone, tended to decompose the sulphides of cal- 
cium with evolution of hydrogen sulphide. The importance of 
pure lime for this insecticide is thus emphasized. An examina- 
tion of commercial lime-sulphur preparations revealed great 
variations in composition. Since field experiments have demon- 
strated that this insecticide derives its chief value from the 
soluble lime-sulphur compounds, commercial preparations should 
be bought on the basis of the strength and composition of their 
supernatant liquid. 

Stewart states that the problem of making concentrated lime- 
sulphur solutions is essentially one of preventing crystallization 
and securing a storable product of high density. He finds that 
the formation of crystals is largely due to an excess of lime and 
exposure to the air when cold. Exposure to the air may be 
avoided by covering the surface of the wash with oil. Arsenite 
of lime, as a supplementary insecticide, has been fotmd to pro- 
duce least decomposition of the sulphur compounds of this wash. 

Haywood found that a one hour period of boiling dissolved 
practically all the sulphur used for this wash. The addition of 
common salt was found to have no effect so far as the sulphur 
compounds of the wash were concerned. 



304 Agricultural Chemistry. 

On theoretical grounds. Haywood recommends the following 
formula for preparing, at minimum cost, a wash with the max- 
imum amount of sulphur in solution and a moderate excess of 
lime: 

Lime 20-22J^ pounds 

Sulphur 20 pounds 

Water 50 gallons 

The mixture is best when boiled by passing steam through it. 
Moderate slaking of the lime was found to have no influence, but 
a comparison of flowers of sulphur and crystallized sulphur 
showed that the crystalline form, even when finely ground, re- 
quired much longer boiling for maximum solution and gave a 
product of variable composition, apparently dependent on the 
size of the particles. 

To determine what changes take place after the wash is ap- 
plied to trees, measured quantities of the clear liquid were ab- 
sorbed on filter papers and dried in the open air exposed to sun- 
light. Analyses at successive stages showed the gradual oxida- 
tion of calcium penta-sulphide into calcium thiosulphate, calcium 
sulphite and finally calcium sulphate, with deposition of free 
sulphur. Wetting the paper daily to simulate the daily wetting 
of branches by dew greatly increased the rapidity of the process. 
Indications Avere, that after four to six months only free sulphur 
and calcium sulphate would be left. Hay^vood believes that the 
exc&ss of caustic lime loosens the scale insects from the tree, and 
that the active agents in killing are sulphur in finely divided 
form, thiosulphate, for a time, and sulphite, which is gradually 
formed by the slow oxidations. 

Self boiled washes, in which the heat for solution is produced 
by the chemical reaction incident to slaking the lime, are un- 
satisfactory, even when a maximum amount of heat is so gen- 
erated. 

Lime, sulphur, salt, soda-wash, in which caustic soda is used 
in addition to lime, has nearly the same composition and action 
as the simpler wash already described. It is less effective, how- 



Insecticides and Belated Suhstwnces. 305 

ever, because it decomposes more slowly and the sodium sulphite 
formed is more subject to loss by washing than is calcium 
sulphite. 

Kerosene has been used as a contact insecticide against scale 
insects. It is applied as a spray to the dormant trees, but is 
frequently injurious. Applied to stagnant pools, it effectually 
suffocates the emerging pupae of mosquitoes; and in the "hop- 
per-dozer" it destroys grasshoppers which are trapped in it, by 
forming an oil film over the tracheae. 

Kerowater sprays were the result of attempts to dilute kero- 
sene before applying it to trees. Kerosene is not miscible with 
water but by forcibly mixing these liquids at the nozzle of the 
spray pump the kerosene was temporarily diluted. 

Kerosene emulsions are comparatively permanent suspensions 
made by mixing kerosene oil with soap solutions. They are not 
true solutions, for the oil can be observed under a microscope as 
droplets suspended in the soap solution. "Well made emulsions 
persist for several hours, and even for days, and facilitate an 
even distribution of the kerosene. Crude petroleum oils, which 
are closely related to kerosene but less volatile than the latter, 
have taken its place to a great extent because of the greater 
efficiency and safety attendant upon their use. 

Miscible oils are preparations of this nature. They are based 
on a standard soap solution with which various proportions of 
different oils are emulsified. Crude oil, a mixture of petroleum 
oils heavier than kerosene; paraffin oil, a lubricating oil from 
petroleum ; and resin oil, from the distillation of resin, are used. 
The crude oils are efficient in 6 2/3 per cent strengths, whereas 
kerosene is inefficient below 20 per cent strength. 

Penny gives the following formula for a standard miscible oil : 

The "Soap Solution." 

Menhaden oil 10 gallons 

Carbolic acid 8 " 

Caustic potash 15 " 

Heat to 290° or 300° F., then gdd kerosene 2 " 

Water 2 " 



30G Agricultural Chemistry. 

From the above soap solution, the miscible oil is prepared ac- 
cording to the following formula : 

Soap solution 3% gallons 

Paraffineoil 40 

Rosin oil *> " 

Water, as required by test. 

In the process of making the soap solution the kerosene should 
be added while the soap is hot. The heavier oils should be stirred 
into the soap solution at moderate temperatures. Freezing tem- 
peratures should be avoided. The amount of water to be added 
is a matter of experiment but it should be used in quantity suffi- 
cient to produce an emulsion of creamy consistency. One gallon 
of the soap solution or emulsifier will make 8 to 14 gallons of 
miscible oil and these 8 to 14 gallons will make from 100 to 210 
gallons of spraj' material, according to dilution. 

Resin soaps, efficient against orange scale insects, are prepared 
by boiling resin with carbonate of soda and diluting the solid 
product with water. 

Fish oil soap and whale oil soap, prepared by boiling the oils 
in potash lye and diluting with water, are effective against plant 
and animal lice, but the commercial preparations are subject to 
great variations in composition. 

Tobacco decoction depends for its value upon the poisonous 
properties of nicotine. This alkaloid is soluble in water, and 
hot water extractions of the stalk and waste of tobacco are used 
as an insecticide. 

Gaseous insecticides are used against insects particularly dif- 
ficult to attack. Hydrocyanic acid gas is by far the mast effec- 
tive substance in this class. It is produced from : — 

Potassium cyanide, pure 1 ounce 

Sulphuric acid, commercial 2 " 

Water 4 " 

This is the quantity recommended for each 100 cubic feet of 
space. The cyanide should be added last, having the mixture in 



Insecticides cmd Relented Substances. 307 

an earthen-ware vessel. Potassium sulphate is formed and the 
poisonous hydrocyanic acid is rapidly liberated as an invisible 
gas. This is an extremely powerful poison, a single breath being 
fatal, and by no means should it be inhaled by the operator. 
To retain the gas and secure efficient action, it should be applied 
in tightly closed rooms or buildings, or in tents specifically pro- 
vided for the purpose, allowing it to act for an hour or more. 
The enclosure should then be opened from the outside and thor- 
oughly aired before being entered, and the strongly acid residue 
from the reaction should be carefully disposed of. 

Carbon bisulphide is a colorless, volatile liquid formed by pass- 
ing sulphur vapors over red hot charcoal. The gas evolved from 
the liquid is heaAder than air, inflammable and fatal to insects 
breathing it. Its chief use is for the destruction of weevils in 
grain. One teaspoonful for each cubic foot of space should be 
placed in a shallow dish at the surface of the grain, and one hour 
allowed for the evaporation of each teaspoonful used. The heavy 
vapors sink through the grain to the bottom of the bin, where 
they may be released by boring holes through the wall. Ants, 
moles, prairie dogs and similar pests are exterminated by placing 
cotton saturated with carbon bisulphide in the heaps or runs and 
covering tightly. Carbon bisulphide should never be brought 
near flames. 

Fungicides are materials utilized for the destruction of para- 
sitic plants. Hyposulphite of soda, lime-sulphur and sulphur 
alone were used in this capacity as early as 1885 against apple 
scab and leaf blight. 

Bordeaux mixture has been the premier fungicide since 1883, 
when Millardet used it against the downy mildew of the grape. 
It was accidentally discovered by observing the flourishing con- 
dition of vines to which lime and copper salts had been applied 
to prevent the theft of grapes in the province of Bordeaux, 
France. Several formula have been superseded generally by 



308 Agricultural Chemistry. 

the so-called "normal" formula, or 1.6 per cent Bordeaux, which 
consists of: 

Copper sulphate 6 lbs. 

Quick lime 4 lbs. 

Water 50 gallons 

The lime should be slightly in excess. This may be accom- 
plished by weighing the pure salts for the mixture, or by testing 
the product. 



'•^''^^*'^'^''^''»^^»^;^ 




Note the beneficial results from the control of potato diseases by Bor- 
deaux mixture. 

The litmus test depends upon the fact that so long as copper 
sulphate is in excess blue litmus will be turned red when moist- 
ened with the Bordeaux mixture. Enough lime should be pres- 
ent so that red litmus is turned blue. 

The ferro-cyanide test may be used also for this purpose. A 
teaspoouful of the clear liquid, obtained by straining if necessary, 
should be added to a few drops of potassium-ferrocyanide solu- 



Insecticides and Related Substmices. 309 

tion in a white porcelain dish. A reddish brown precipitate or 
color indicates the presence of soluble copper salts, and lime 
should be added to the mixture until this no longer appears. 

The fungicidal properties of Bordeaux mixture are chiefly due 
to the insoluble compounds formed and it is important to keejj 
these thoroughly in suspension. To facilitate this, the copper 
sulphate and lime should be dissolved separately, each in one-half 
the water, and vfhen the lime is cool, they should be poured to- 
gether with constant stirring. In this way, the dilute solutions 
react to form a fine suspension which will not settle for several 
hours. The chemistry of Bordeaux mixture has not been thor- 
oughly investigated. According to Lodeman, when the copper 
sulphate is just neutralized, most of the copper is probably pre- 
cipitated as a hydrate ; but excess of lime added to a concentrated 
"mixture" forms another compound which may be a basic sul- 
phate of copper and lime. 

Soda Bordeaux, made with caustic soda in place of lime in 
the regular formula, has given satisfactory results. 

Copper ammonium sulphate, a clear blue solution formed 
from copper sulphate and ammonia, also called "eau celeste," 
has been applied as a fungicide, but its caustic action renders 
it unsafe. Copper carbonate dissolved in ammonia, however, has 
given good results. It should be freshly prepared, as the am- 
monia may volatilize on standing, causing the copper to fall out 
of solution. 

Copper sulphate has been applied to dormant trees and green- 
house plants as a dilute solution, but it p'ossesses a strongly acid 
reaction and should be used with care. Smut on grains is de- 
stroyed by this fungicide. A one to two hour immersion of oats 
in a 0.5 to 1.0 per cent solution may be safely practiced, but 
stronger applications retard germination. 

Potassium sulphide is used against mildews at the rate of 
one-half ounce to one gallon of water. Strong solutions are 
destructive to plants. Potash lye and formaldehyde-glycerine 



310 Agricultural Chemistry. 

mixture, properly diluted, have proved valuable fungicides under 
certain conditions. 

Formalin or formaldehyde, is a most efficient agent for destroy- 
ing smut spores on grain. The seed should be immersed for ten 
minutes in a solution of 1 pint of ''40 per cent" formalin to 
20 gallons of water. Stronger solutions have been found in- 
jurious to the germinating power of barley. The seed should be 
spread and finall}' mixed so as to dry with not more than two 
to three hours contact with the formalin. 

Disinfectants are substances which accomplish the total de- 
struction of the germs of infectious diseases. They may also act 
as deodorants or destroyers of foul odors. 

Antiseptics prevent decomposition or putrefaction by arrest- 
ing the development of germs, but do not necessarily destroy 
them. Disinfectants in weak solutions may act as antiseptics. 
Refrigeration, common salt and sugar, all of which are largely 
used in preserving fruits, meats, etc., are good examples of anti- 
septics. 

Formaldehyde is perhaps the most commonly used chemical 
disinfectant. It is a product of the oxidation of wood alcohol 
and is put upon the market in a 38 to 40 ])er cent solution in 
water. A five per cent solution made from this should be mixed 
with any solid matter to be disinfected. Gaseous formalde- 
hyde is used for disinfecting inclosed space and porous solid 
matter in bulk. The gas should be delivered into a tightly closed 
compartment in one of the following ways: Formalin may be 
heated under pressure or in a simple retort and the gas piped 
into the space; formalin may be sprayed upon sheets or other 
extensive surfaces in the space to be disinfected and the gas 
liberated by simple evaporation ; six parts of formalin may be 
poured upon five parts by weight of chemically pure potassium 
permanganate. In the last case, heat is generated by chemical 
reaction and 50 per cent of the formaldehyde is liberated as a 
gas. Ten ounces of formalin are necessary for each 1000 cubic 



Insecticides and Ji elated Substances. 311 

feet of space in the first two cases and twice as much must be used 
in the permanganate method. This disinfectant also acts as a 
deodorant. 

Paraform is a condensed form of fonnaldehyde put up as a 
powder or as pastils. Two ounces of paraform liberate gas suf- 
ficient to disinfect 1000 cubic feet of space. 

Mercuric chloride or corrosive sublimate is a poisonous, white, 
crystalline salt. It is usually put up in tablet form with am- 
monium chloride to facilitate dissolving in water. Strengths of 
1 to 500 to 1 to 1000 are used, the greater strength being neces- 
sary to destroy bacterial spores. This is a powerful stomachic 
poisoning and must be handled wdth care. It forms insoluble 
compounds with proteins and hence raw eggs and milk are given 
as antidotes. On account of its chemical affinity for proteins, 
unless liberally used it has little disinfecting power when applied 
to excreta, blood and similar protein containing materials. Solu- 
tions of this salt should be iLsed only in glass or earthern ware, 
as it reacts with tin and other common metals. 

Chloride of lime (bleaching powder) is both a disinfectant and 
deodorizer. It is prepared bj' passing chlorine gas over slaked 
lime. The compound decomposes rapidly on exposure to the 
air and hence is put up in hermetically sealed containers and is 
reliable only when freshly removed from these. 

Carbolic acid is a derivative of benzene, a hydrocarbon which 
forms the basis of the coal tar dyes. At ordinary temperatures 
it has the crystalline form of long, white needles. One part of 
water to 9 parts of the crystals produces a liquid, in which form 
it is commonly dispensed. By dissolving in warm water a solu- 
tion of slightly over 6 per cent carbolic acid can be made. This 
is used as a spray and wash. Crude carbolic acid is a crude prep- 
aration from coal tar distillation, the latter substance being the 
liquid by-product in the production of gas and coke from coal. 
This disinfectant is a mixture of various coal tar oils and so- 
called "cresylic acid," and contains little or no true carbolic 
acid. The disinfecting power is due to cresols of the ''cresylic 



312 Agricultural Chemistry. 



acid," bodies related to carbolic acid. Therefore the "cresylic 
acid" content of the crude material should be known and from 
this a 2 per cent solution of the constituent made. The undis- 
solved cresols that are present necessitate a thorough mixing 
while spraying in order to facilitate an even distribution of the 
material 

Cresol (trikresol) is supplied to the trade from the coal tar 
industry in varying degrees of purity. It contains bodies of 
the same general composition, but which are superior to car- 
bolic acid as disinfectants. Grades containing less than 90 per 
cent of "cresylic acid" (cresols) are undesirable because of the 
suppression of solubility of the cresols by the oils usually present 
as impurities. A 2 per cent cresol solution is considered superior 
to a 5 per cent solution of carbolic acid. 

Liquid carbolic acid is a mixture of cresols, usually 90 to 
98 per cent pure, which should be bought on guaranteed content 
of "cresylic acid." Compound solution of cresol is a mixture 
of equal parts of cresol and linseed-oil-potash soap. It is ap- 
plied like cresol with the added advantage of greater solubility 
in water. 

These coal tar compounds are the basis also of a number of 
commercial, soluble disinfectants and dips, such as creolin, lysol. 
solveol, Car-Sul dip, carboleum, cresol, disinfectall, germol, and 
zenoleum. Fly removers, applied to animals for protection 
against flies, have been prepared from these substances. Light 
coal tar oil for this purpose has given the most satisfaction as 
to persistence and freedom from gimiming on the animal's coat. 

Creosote preparations for antiseptic treatment of timbers 
against bacteria and fungi are the heavier fractions of coal tar 
oil and carry carbolic acid, the cresols, naphthalene, (also used 
in moth balls), anthracene, and similar high-boiling hydrocarbons 
and carbolic-acid-like bodies. 

Deodorants include some of the above materials, such as 
chloride; of lime, which destroy the causal substance through 
chemical action. Other substances merely cover up the offensive 



1 



Insecticides and Belcded Substances. 313 

odor by the odor they themselves produce Charcoal is a 
deodorant by virtue of its great absorptive capacity for gases. 
It acts by mechanical absorption of offensive gases into its pores. 
Incidental materials. Use is often made of arsenite of soda, 
common salt, carbolic acid, sulphuric acid and other compounds, 
as weed destroyers. Iron sulphate solution, prepared by dissolv- 
ing 100 pounds of the granulated salt in 50 gallons of water for 
each acre of land has been successfully used in eradicating wild 
mustard. Untoward effects of these substances on the soil can 
be corrected in many cases by applications of lime. Copper sul- 
phate applied to reservoirs at the rate of one part of salt to from 
one million to ten million parts of water has been extensively 
used in destroying algae growth. 



1 



APPENDIX 



COMPOSITION OF SOILS. 

Snyder gives the foUoAving average composition of 200 fertile 
soils; analysis was made by strong hydrochloric acid. 

Insoluble matter 79.95 Per cent. 

Potash 0.29 

Soda 0.25 

Lime 2.16 

Magnesia . 55 

Iron oxide 2 . 08 

Alumina. 5.20 

Phosphor acid . 24 

Sulphur trioxide 0.03 

Carbone dioxide 1.12 

Volatile matter 7 . 00 

99.47 
Volatile matter containing: 

Humus 3 . 35 

Nitrogen 29 



316 



Agricultural Chemistry. 
Fertilizing Constituents in One Ton of Material. 



Feed 



Nitrogen 
lbs. 



Phosphoric 
acid, lbs. 



Potash 
lbs. 



Dry matter 
lbs. 



Concentrates 

Corn , 

Corn bran 

Hominy chops 

Gluten feed 

Wlieat 

Wheat middlings 

Rye 

Barley 

Malt sprouts 

Brewers' grains (dried) 

Oat feed 

Cotton seed meal 

Peas 

Roughage 

Corn stover 

Timothy hay 

Red clover hay (medium). 

Red clover hay (mammoth) 

Crimson clover hay 

Alfalfa hay 

Silage 

Corn 

Straw- 
Oat 

Barley 

Roots and Tubers 

Potatoes 

Beet, common 

Beet, sugar 

Rutabaga 

Turnip 

Miscellaneous 

Cabbage 

Rape 



36.4 
32.6 
32.6 
76.8 
47.2 
52,6 
35.2 
30.2 
71.0 
72.4 
34.4 
13.5 
fil.G 

20.8 
25.2 
41.4 
44.6 
41-0 
43.8 



12.4 
26.2 

6.4 
4.8 
4.4 
3.8 
36 

7.6 
9.0 



14.0 
24.2 
19.6 
8.2 
15.8 
19.0 
16.4 
15.8 
28.6 
20.6 
18.2 
57.6 
1(5.4 

5.8 
10.6 

7.6 
11.0 

8.0 
10.2 

2.2 

4.0 
6.0 

2.4 
1.8 



2.2 
3.0 



8.0 
13.6 

9.8 

0.6 
10.0 
12.6 
10.8 

9.6 
32.6 

1.8 
10.6 
17.4 
19.8 

28.0 
18.0 
44.0 
24.4 
26.2 
33.6 

7.4 

24.8 
41.8 

9.2 

8.8 
9.6 
9.8 
7.8 

8.6 
7.2 



764 

818 

844 
732 
748 
714 
714 
760 
810 
734 
823 
720 

816 
726 
684 
7-2 
672 
850 

441 



1,710 
1,716 

500 
245 
360 
218 
184 

220 
290 



Appendix. 



317 



COMPOSITION OF FERTILIZERS. 

Composition of fertilizer materials supplying nitrogen. 



Nitrate of poda 

Sulphate of ammonia. . . . 
Dried blood (high grade 
Concentrated tankage. . . 

Tankage (bone) 

Nitrogenous guano 



Per cent 
Nitrogen 



15.5-16 
19 -20.5 
12 -14 
11 -12.5 
5-6 
3-7 



Per cent 

Phosphoric 

acid 



1 - 2 

11 - 14 

9 - 19 



Per cent 
Potash 



2-4 



Composition of fertilizing materials supplying phosphoric acid. 



S. Carolina rock (ground) (floats) 
S. Carolina rock (dissolved).... 

Florida rock 

Thomas slag 

Ground bone . 

Steamed bone 

Bone black 



Per cent 

Phosphoric 

acid 



25 - 30 
12 - 16 
25 - SO 
18 - 23 
20 - 25 
22 - 29 
32 - 36 



Per cent 
Nitrogen 



2.5 - 4.5 
1.5 - 2.5 



Composition of fertilizer materials supplying potash. 



Per cent 
Potash 



Per cent 
Nitrogen 



Per cent 

Phosphoric 

acid 



Muriate of potash (80-85 per cent pure) . 

Sulphate of potash ( high grade) 

Sulphate of potash (low grade ) 

Kainit 

Tobacco stems 

Wood ashes 



50 - 53 

48 - 52 
28 - 30 
12 - 13 

3-8 

4 - 



3-5 
1 - 2 



318 



Agricultural Chemistry. 



COMPOSITION OF FEEDING STUFFS. 

The following brief table gives the composition of some typical 
feeding materials (taken from "The Feeding of Animals," 
Jordan, Appendix) : 



I 



£► " 

!> 5 



Fodders 

Corn fodder (green) 

" " (field cured). . . 

Cornsilapre 

Timothy (green) 

'■ hay 

Alfalfa (green) 

hay 

Clover hay (red) 1 15.3 

Roots 

Turnips 

Rutabagas 

Grains 

Corn 

Barley 

Oats 

Wheat 

Mill Pkoducts 

Corn meal 15 . 

Corn-and-cob meal 15.1 

Wheat flour 12.4 

Wheat bran 11.9 

Gluten feed 7.1 

Oat feed 7.7 

Brewers' grains (dried) 8.2 

Linseed meal (new process) 10.0 

Malt sprouts 5.0 



79.3 
42.2 
79.1 
61.6 
13.2 
71.8 
8.4 



90. o 
88.6 

10.9 
10.9 
11. 
10.5 





s 


-IJ 


a> ^ 


c 


o c 


JS <U 


(i <v 


00 « 


PL, « 


<5 u 


gj fc. 


a> 


-a « 


a 


a ft 




tH 




o 


1.2 


1.8 


2.7 


4.5 


1.4 


1.7 


2.1 


3.1 


4.4 


5.9 


2.7 


4.8 


7.4 


14.3 


6.2 


12.3 


.8 


1.1 


1.2 


1.2 


1.5 


10.5 


2.4 


12.4 


.) . 


11.8 


1.8 


11.9 


1.4 


9.2 


1.5 


8.5 


.5 


10.8 


5.8 


15.4 


1.1 


24.0 


3.7 


16.0 


3.6 


19.9 


5.2 


36.1 


6.4 


27.6 



at 



i « c 

C 03 0! 

<u I-, V 

O X t- 

u <i> 9i 






5.0 


12.2 


14.3 


34.7 


6.0 


11.0 


11.8 


20.2 


29.0 


45.0 


7.4 


12.3 


25.0 


42.7 


24.8 


38.1 


1.2 


6.2 


1.3 


7.5 


2.1 


69.6 


2.7 


69.8 


9.5 


59.7 


1.8 


71.9 


1.9 


68.7 


6.6 


64.8 


.2 


75. 


9.0 


53 9 


5.3 


51.2 


6.1 


59.4 


11. 


51.7 


8.4 


36.7 


10.9 


47.1 



.6 
1.6 

.8 
1.2 
2.5 
1.0 
2.2 
3*3 

.2 
.2 

5.4 
1.8 
5. 
2.1 

3.8 
3.5 
1.1 
4.0 
10.6 
7.1 
5.6 
3.6 
3.0 



Appendix. 



319 



AVERAGE COEFFICIENTS OF DIGESTIBILITY. 

A brief table giving the coefficients of digestibillity of important feeding 
materials. Taken from the " Feeding of Animals" (Jordan). 

Digestion by Ruminants. 



Feed 


«^ 

>- 

-^ « 
Do- 

Q 


Organic 
matter 
per cent 


Ash 
per cent 


Crude protein 
per cent 


Fiber 
per cent 


Nitrogen-free 
extract 
per cent 


5g 

0) u 


Fodders. 

Corn fodder (green) 

" " (field cured) 
Corn silage 


67.8 
68.2 
70.8 
63.5 
56.6 
67.0 
5S.f) 

02.8 
87.2 

89.4 


69.8 
70.7 
73.6 
65.6 
57.9 
64.0 
60.7 

96.1 
91.1 

89. () 
86.0 
71.0 

89.6 
79.8 
65.7 
87.3 
65.3 
65.4 

81.8 
67.2 


35.6 
30.6 
30.3 
32.2 
32^8 

39' 5 

58.6 
31.2 


59.7 
56.1 
56.0 
48.1 
46.9 
81.0 
72.0 

89.7 
80.3 

67.9 
70.0 
78.0 

67.9 
55.6 
77.8 
85.6 
81.1 
79.3 

85.2 

80.2 


60.2 
65.8 
70.0 
55.6 
52.5 
41.0 
46.0 

103.0 
74.2 

58.0 
50.0 
26.0 

'45' 7' 

28.6 
78.0 
42.6 
52.6 

80.4 
32.9 


73.7 
72.7 
76.1 
65.7 
62.3 
72.0 
()9.2 

96.5 
94.7 

94.6 
92.0 

77.0 

94.6 
87.6 
69.4 
89.2 
67.4 
57.8 

86.1 
68.1 


74.1 
73.9 

82.4 


Timothy (green) 

" hay 


53.1 
52.2 


Alfalfa (green) 


45.0 


hay 

Roots. 

Turnips 

Rutabagas 

Grains. 

Corn 


51.0 

87.5 
84.2 

92.1 


Barley 


89.0 


Oat ;■;... 




83.0 


Mill Products. 
Corn meal 


89.4 
78.7 
62.3 
86.3 
62.0 
61.6 

79.2 
67.1 


92.1 


Corn and cob meal 

Wheat bran 


84.1 
68.0 


Gluten feed 


84.4 


Oat feed 


89.0 


Brewers' grains (dried) . . 

Linseed meal (new proc- 

ess) 


91.1 
96.6 


Malt sprouts 


104.6 



Timothy (hay) 
Alfalfa "(hay). . 
Oat (grain).... 
Barley " 
Corn " ... 



Digestion by Horses. 
34.0 



43.5 



i.4 



44.1 
58.0 
69.0 
87.0 
89.0 



Digestion by Swine. 



Barley 

Corn (unground ) . . . . 
Corn (finely ground) , 
Corn and cob meal . . . 
Wheat (unground). . . 

Wheat ( cracked ) 

' ' bran 

Linseed meal 



80.1 
89.7 
89.5 
75.6 
72.0 
82.0 
65.8 
77.5 



80.3 
91.3 
91.2 

76.7 



5.4 



44.0 
50.0 



10.0 




47.3 
70.0 
75.0 
87.0 
95.7 



47.3 
14.0 
71.0 
42.0 
73.1 



86.6 


57.0 


93.9 


77.6 


94 . 2 


81.7 


83.6 


82.0 


74.0 


60.0 


83.0 


70.0 


65.5 


71.8 


85.0 


80.0 



320 



Agricultural Chemistry. 



1 



WOLFF'S FEEDING STANDARDS. 

Per day per 1000 lbs. live weight. 



Kind of animal 


Total 

dry 

matter 


Digestible organic matter 


Nutritive 


Protein 


Carbo- 
hydrates 


Fat 


ratio 1 : 


1. Oxen 

At rest 


Lbs. 
18 
22 
25 

28 

30 
30 
26 

25 
29 

20 
23 


Lbs. 
0.7 
1.4 

2.0 

2.8 

2.5 
3.0 

2.7 

1.6 
2.5 

1.2 
1.5 
2.9 

3.0 
3.5 

1.5 
2.5 
2.5 

4.5 
4.0 

2.7 


■ 
Lbs. Lbs. 
8 1 "1 


11.8 
7.7 
6.5 
5.3 

6.5 
5.4 
6.2 

6.7 
5.7 

9 1 


Light work 


10.0 
11.5 
13.0 

15.0 
14.5 
15.0 

10.0 
13.0 

10.5 


0.3 
0.5 
0.8 

0.5 
0.7 

0.7 

0.3 
0.5 

n 9 


Moderate work 


Severe work 


2. Fattening bovines 

First period 


Seconal period 


Third period 


."{. Milch cows 

Daily milk yield 11 lbs. 

Daily milk 'yield 22 lbs. 
4. Sheep " 

Coarse wool 


Fine wool 


12.0 n^ 


8 5 


Ewes, suckling lambs 

Fattening sheep 

First period 

Second period 

5. Horses 

Light work 


25 

30 

28 

20 
26 
22 

36 
32 
25 


15.0 

15.0 
14.5 

9.5 
13.3 

15.5 

25.0 
24.0 
18.0 


0.5 

0.5 
0.6 

0.4 

0.8 
0.4 

0.7 
0.5 
0.4 


5.6 

5.4 
4.5 

7 


Heavy work 

(j. Brood sows 

7. Fattening swine 

Fir.«t period 

Second period 

Third period 


6.0 
6.6 

5.9 
6.3 
7.0 



Appendix. 



321 



WOLFF'S FEEDING STANDARDS (Continued). 



Kind of animal 
Age in months 



Live 


Total 


weight 

per 

head 


dry 
matter 


Lbs. 


Lbs. 


150 


23 


300 


24 


500 


27 


700 


26 


900 


26 


165 


23 


330 


24 


550 


25 


750 


24 


935 


24 


60 


25 


75 


25 


85 


23 


90 


22 


100 


22 


65 


26 


85 


26 


100 


24 


120 


23 


150 


22 


45 


44 


100 


35 


120 


32 


175 


28 


260 


25 


45 


44 


110 


35 


150 


33 


200 


30 


275 


26 



Digestible organic matter 



Protein 



Carbo- 
hydrates 



Fat 



Nutritive 
ratio 1: 



Growing cattle 
Dairy brkeds. 

2-3 

3-6 

6-12 

12—18 

18—24 

Beef brekds. 

2-3 

3-6 

6—12 

12—18 

18—24 

<iro wilier sheep 
Wool breeds. 

4-6 

6—8 

8—11 

11-15 

15-20 

Mutton breeds. 

4—6 

6-8 

8-11 

11-15 

15—20 

Growing swine. 
Breeding stock. 

2-3 

3-5 

5-6 

6-8 

8-12 

Growing Fattening 
Animals. 

2-3 

3-5 

5—6 

6—8 

8-12 



Lbs. 

4.0 
3.0 
2.0 
1.8 
1.5 

4.2 
3.5 
2.5 

2.0 

1.8 



Lbs. 

13.0 
12.8 
12.5 
12.5 
12.0 

13.0 
12.8 
13.2 

12.5 
12.0 



3.4 


15.4 


2.8 


13.8 


2.1 


11.5 


1.8 


11.2 


1.5 


10.8 


4.4 


15.5 


3.5 


15.0 


3.0 


• 14.3 


2.2 


12.6 


2.0 


12.0 


7.6 


28.0 


5.0 


23.1 


3 7 


21.3 


2.8 


18.7 


2.1 


15.3 


7.6 


28.0 


5.0 


23.1 


4.3 


22.3 


3.6 


20.5 


3.0 


18.3 



Lbs. 

2.0 
1.0 
0.5 
0.4 
0.3 

2.0 
1.5 
0.7 
0.5 
0.4 



0.7 
6 
0.5 
0.4 
0.3 



1.0 
0.8 
0.4 
0.3 
0.2 



1.0 

0.8 
0.6 
0.4 
0.3 



4.5 
5.1 

6.8 
7.5 

8.5 

4.2 

4.7 
6.0 

6.8 

7.2 



5.0 
5.4 
6.0 
7.0 

7.7 

4.0 
4.8 
5.2 
6.3 
6.5 



4.0 
5.0 
6.0 
730 
7.5 



4.0 
5.0 
5.5 
6.0 
6.4 



:122 



Agricultural Chemistry. 



PRODUCTION VALUES PER 100 POUNDS. 

A table ginng the productive value of feeds for fattening pur- 
poses. Computed according to Kellner. 



■ 


Total 

Dry 

Matter 


Total 
Crude 
Fiber 


Digestible 


c 


Feeding Stuff 


s 

o 
u 


as 




"3 a> c 

Oh 


Ureen Fodder and Siiajje: 
Alfalfa 


Lbs. 

28.2 
29.2 
20.7 
25.6 
28.9 
23.4 
38.4 

91.6 
84.7 
57.8 
59 5 
89.3 
92.3 
84.0 
88.7 
86.8 

90.8 
92.9 
90.4 

11.4 
9.1 

21.1 
9.5 

89.1 
89.1 
84.9 
89.0 
88.4 
89.5 

24.3 
91.8 
91.9 
91.8 

90.8 
90.1 
89.8 
88.2 
88.5 


Lbs. 
7.4 
8.1 
5.0 
5.8 
9.2 
11.6 
11.8 

25.0 
24.8 
14.3 
19.7 
20.1 
27.7 
27.2 
22.3 
29.6 

37.0 
38.9 
38.1 

1.3 

8 
0.6 

1 2 

2.7 
2.1 
6.6 
9.5 
1.7 
1.8 

3.8 
5.6 
6.4 
61 

8.9 
8.8 
10.7 
3.3 
9.0 


Lbs. 
2.50 
2.21 
0.41 
1.21 
1.33 
1.44 
1.04 

6.93 
5.41 
2.13 
1.80 
8.57 
3 00 
2.59 
7.68 
2.05 

1.09 
0.63 
0.37 

0.37 
0.14 
0.45 
0.22 

8.37 
6.79 
4.53 
8.36 
8.12 
8.90 

3.81 
35.15 
19.95 
21.56 

27.53 
29.26 
12.36 
11.35 
10,21 


Lbs. 

11.20 

14.82 

12.08 

14.57 

15.63 

14.11 

21.22 

37.33 
38.15 
32.34 
33.16 
:s8.40 
51.67 
33.35 
38.72 
43.72 

38.64 
40.58 
36.30 

7.83 

5.65 

16.43 

6.46 

64.83 
66.12 
60.06 
48.34 
69.73 
69.21 

9.37 
16.52 
54.22 
43.02 

32.81 
38.72 
43.50 
52.40 
41.23 


Lbs. 
0.41 
0.69 
0.37 
0.88 
0.36 
0.44 
0.64 

1.38 
1.81 
1.15 
0.57 
1.51 
1.34 
1.67 
1.54 
1.43 

0.76 
0..38 
0.40 

0.22 
0.11 


10 80 


Clover— Red 


14.52 


Corn Fodder 


11.02 


" Silage 


14.26 


Hungarian Grass 


13.14 


Rve 


10.31 


Timothy 


17.80 


Hav and Dry Coarse Fodders: 
Alfalfa Hav 


34.41 


Clover Hay — Red 


34.73 


Corn F.dder (field cured) 

" Stover 


30.53 
26.53 


Cow Pea Hav 


42.76 


Hungarian Hav 


44.03 


Oat Hav ' 


36 97 


Soy Bean Hay 


38.65 


Timothy Hay". 


33.56 


Straws; 
Oat 


21.21 


Rve 


20.87 




16.56 


Roots, etc.: 
Carrots 


7.82 


Manirel-wurzels 


4.62 


Potatoes 


18.05 


Turnips 


0.11 

1.60 
4.97 
2.94 
4.18 
1.36 
1.68 

1.38 
12.58 

5.35 
11.87 

7.06 
2.90 
1.16 
1.79 
1 2.87 


5.74 


Grains: 
Barley 


80.75 


Corn 


88.84 


Corn and Cob Meal 


72 05 


Oat 


66.27 


Rve 


81.72 


Wheat 


82. 6S 


By Prdducts: 
Brewers' Grains — wet 


14.82 


Cottonseed meal 


84.20 


Gluten Feed— drv 

" Meal, Buffalo 

Unseed meal: 

Old Process 


79.32 
85.46 

78.92 


New " 


74.67 


Malt Sprouts 


46.33 


Rve Bran 


56.65 


Wheat Bran 


48.23 



Appendix. 



32; 



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1 



INDEX 



Abomasuni, 220. 
Acid, definition of, 16. 
Acids, organic in plants, 99. 
Adult animal, 253. 
Aerobic organisms, 128. 
Albumin, definiton of, 100. 

in plants, 101. 

in animals, 207. 

in milk, 271. 
Albuminoids, definition of, 207. 

in animals, 207. 
Alinit, 60. 
Alkali, "black," 76. 

tolerance of plant to, 77. 

"white," 76. 
.A.Iuminum in plants, 108. 
Alkaloids, 103. 
Amides, in plants, 102. 

in animals, 208. 
Amines, in plants, 103. 
Amino-acids, in plants, 102. 

in animals, 208. 
Ammonia, in the air, 31. 

in water, 32. 

loss from manure, 127. 
Ammonium sulphate, 149. 
Amylopsin, 223. 
Anaerobic organisms, 128. 
Animal, constituents, 206. 

manure, 112. 

action on soil, 42. 

composition of bodies, 209. 



Antiseptics, 310. 

in milk, 279. 
Ants, in soil formation, 43. 
Apples, 195. 
Apatite, 38. 
Argon, 30. 

Armsby's feeding standards, 242. 
Arsenic, as insecticide, 294. 
Artificial manures, 146. 
Ash, in animal products, 210. 

in feeds, 103, 218. ' 

importance to animals,. 218. 
Assimilation of carbon dioxide, 86. 
Ass's milk, 278. 
Atmosphere, 23. 

Available phosphoric acid in fer- 
tilizers, 155. 

energy, 237. 
Avenin, 258. 
Ayrshire milk, 270, 280. 

Bacteria, action in digestion, 224. 

action in milk, 278. 

assimilation of niti'ogen, 30. 
Barium, in plants, 109. 
Barley, grain cohiposition, 183. 

straw composition, 184. 
Base, definition of, 16. 
Basic slag, 157. 
Beans, grain composition, 187. 

field, 187. 

soy, 187. 



328 



Agncnltural Chemistry. 



^ 



Beets, 194. 

Bile, 223. 

Bleaching powders, 311. 

Blood, 211. 

dried for manure, 150. 
Boiler scale, 71. 
Bone ash, 156. 
Bones, 156, 212. 
Boracic acid, 279. 
Bordeaux mixture, 307. 
Bran, wheat, 181. 
Bran, corn, 186. 
Brewer's grains, 184. 
Buckwheat, 189. 
Butter, 283. 
Butter milk, 285. 



Cabbage, 196. 

Calcium, function in plants, 106. 

occurrence, 12. 

carbonate, 37. 

in soils, 38. 

cyanamide, 150. 

nitrate, 150. 
Caliche, 149. 
Calf, composition, 210. 
Calorie, definition, 8. 
Cane sugar, 90. 
Capillarity. 53. 
Carbohydrates, in i)lants, 89. 

in animals, 208. 

function in animals, 217. 
Carbolic acid, 311. 
Carbon, occurrence, 9. 

dioxide in air, 30. 

assimilation, 86. 

in decay, 47. 

respiratory, 226. 

in soil gases, 60. 

as a solvent. 43. 
Carbon disulphide, 307. 



Carcase, composition of, 209. 

in increase, 211. 
Cartilage, 214. 
Casein, 271. 
Castor bean. 189. 

oil, 189. 
Cellulose, 93. 
Cereals, 173. 
Chalk, 38. 
Cheese, 288. 

Chemical changes in soil, 55. 
Chemical manures, 147. 
Chili saltpeter, 149. 
Chlorine, bleaching action, 15. 

as a disinfectant, 311. 

function in plants, 108. 

occurrence, 14. 
Chlorophyll, 86. 
Churning, 283. 

Clay, occurrence and composition, 
45. 

physical and chemical proper- 
ties, 48. 
Climate, influence on plants, 200. 
Clovers, 191. 
Collagen, 214. 
Colloids, 53. 
Colostrum, 249. 
Cooking food, 232. 
Combustion, si)cntaneous, 96. 
Condensed milk, 286. 
Connecting tissue, 214. 
Constituents of plants, 22. 
Copper suli)hate, 309. 
Corn, composition, 185. 

stover, 139. 

silage, 192. 
Cotton seed meal. l.')l, 188. 

oil, 188. 
Cow, digestion in, 220. 

ration for. 263. 
Cream, 280. 



Index. 



329 



Creosote, 312. 
Creatin, 227. 
Creatinin, 227. 
Cresol, 312. 
Crops, classification, 173. 

residues, 180. 
Crude fiber of feeds, 174. 



Dairy, 267. 

Denitrification, 59. 
Dent corn, 185. 
Dextrine, 93. 
Dextrose, 89. 
Diastase, 80. 
Diffusion in soils, 52. 
Digestibility of feeds, 231. 
Digestion, 218. 

coefficient of, 129. 

energy consumed in, 237. 
Dips, 312. 
Disinfectants, 310. 
Dissolved bones, 156. 

phosphate rock, 154. 
Dolomite, 37. 
Drainage, 63. 



Eggs, 210. 

Elastin, 214. 

Elements, 7. 

Elimination from animal, 227. 

Energy, lost in digestion, 238. 

utilized in labor, 255. 
Ensilage, 192. 
Enzymes, 79, 219. 
Ether extract of foods, 175, 236. 
Evaporation, from plants, 85. 

soil, 54. 
Ewe's milk, 249. 
Excretion, in animals, 227. 

in plants, 83. 



Fallow, 54. 

Farmyard manure, 112. 

composition, 113. 

decomposition of, 122. 

preservation of, 129. 
Fat, digestion of, 223. 

heat producing value of, 216. 

in animal body, 213. 

in feeds, 95. 

of milk, 269. 
Fat globules in milk, 270. 
Fats, nature of, 96. 
Fatty acids, saturated, 96. 

unsaturated, 96. 
Fat production, from proteins, 265- 

from carbohydrates, 265. 

starch equivalent, 240. 
Fattening animals, 258. 

rations, 259. 
Feathers, 206. 
Feeding standards, 229. 
Feldspar, 36. 
Fermentation, of manure, 127. 

in silo, 193. 
Fertilizers, 146. 

laws, ]71. 

selection of, 165. 
Flax, 188. 
Flowers, 87. 
Fluorine, 206. 
Fodder crops, 190. 
Food constituents, function of, 215. 

composition, 174. 

digestibility, 231. 

economy of, 264. 

influence on butter, 275. 

influence on milk, 275. 

manurial value, 115. 

production value, 239. 
Formaldehyde, 310. 
Frost, action of, 41. 
Fruits, 195. 



830 



Agricultural Chemistry, 



Fuel value, animal products, 8. 

food constituents, 237. 
Fumigation, 306. 

tobacco, 306. 
Fungi. 307. 
Fungicides, 307. 

Galactase, 289. 

(Jalactans, 93. 

(Galactose, 90. 

Gases, in soil, 60. 

Gastric juice, 220. 

Germination, of seeds, 79. 

Glaciers, action of, 39. 

Globulins, 100. 

Glucose, 89. 

Glutamin, 102. 

Glycerine, 95. 

Glycogen, 208. 

Goats, digestion in, 231. 

Grapes, 77. 

Grasses, composition, 190. 

digestibility, 231. 
Green manuring, 143. 
Gravel, 53. 
Grits, 38. 
Guano, bat, 157. 

fish, 157. 
Gypsum, 162. 

Haemoglobin, 212. 
Hair, 152. 

Hardness, of water, 71. 
Hay crop, 190. 

composition, 191. 

digestibility of, 197. 
Heat, of animal, 254. 

of combustion, 8. 

relation to plant, 87. 

relation to soil, 48. 
Hellebore, 302. 
Hemp seed, 189. 



Hoof meal, 152. 
Horn meal, 152. 
Horse, digestion in, 220. 

labor ration, 255. 

manure, 113. 
Humus, function in soil, 46. 

physical properties, 48. 
Hydrated silicates, 37. 
Hydrates of iron and aluminum, 

37. 
Hydrocyanic acid, 306. 
Hydrogen, occurrence, 9. 

Igneous rocks, 35. 

Increase, ■while fattening, 211. 
Indian corn, 185. 
Insecticides, 294, 
Iron, function in plant, 107. 

in soils, 36. 

occurrence, 14. 
Irrigation waters, 76. 

Jersey milk, 270, 280. 

Kainit, 159. 
Keratin, 207. 

Labor ration, 255. 

Labradorite, 36. 

Lactic acid, in milk, 278. 

in silage, 193. 
Lactose, 271. 
Lead, action of water on, 72. 

arsenate, 300. 
Leaves, function of, 87. 
Leather, 152. 
Lecithin, 97. 
Leguminous crops, 191. 
Leucine, 102. 
Lentils, 260. 

Light, action on plants, 80. 
Lignin, 93. 



Index. 



331 



Lime, as a manure, 161, 

in foods, 266. 

in soil, 38. 
Limestone, 46. 
Linseed, 188. 
Lipase, 80, 223. 
Litter, 118. 
Loco-weed, 109. 
London purple, 298. 
Lupines, 144. 
Lysol, 312. 

Magnesium, functions of, 106. 

occurrence, 14. 

silicates, 37. 
Maintenance ration, 253. 
Maltose, 90. 
Malt, 183. 
Maltsprouts, 183. 
Mangolds, 194. 
Manure, farmyard, 112. 

application, 134. 

composition, 113. 

decomposition, 127. 

yield by animals, 114. 
Manurial value of feeds, 115. 
Maple sap, 90. 
Marl, 45. 

Marrow of bones, 212. 
Margarine, 285. 
Meadow hay, 191. 
Metamorphic rocks, 35. 
Methane, production in digestion, 

238. 
Mica, 36. 
Milk, albumin, 271. 

ash, 272. 

cows, 274. 

composition of, 273. 

fat of, 269. 

physical properties, 273. 

powders, 286. 



preservation, 278. 

souring, 278. 

sugar, 271. 

of various animals, 268. 
Milking cows, rations for, 263. 
Mineral phosphates, 153. 
Minerals, 36. 

Miscellaneous materials, 313. 
Muscular tissue, 213. 
Muriate of potash, 159. 

Nitrate, of potasli, 149. 

of soda, 149. 
Nitrates, conservation of, 128. 

loss by drainage, 66. 

produced in soil, 57. 
Nitric acid, in air, 31. 

in rain, 32. 
Nitrification, 57. 
Nitro-bacter, 29. 
Nitrogen, in air, 27. 

assimilation, 27. 

fixation, 27. 

occurrence, 10. 

stored up, by animals, 207. 
by plants, 205. 

voided by animals, 216. 
Nodules on legumes, 45. 
Nucleins, 100. 
Nucleic acid, 100. 
Nutrition, of animals, 214. 

of plants, 18. 
Nutritive ratio, 234. 

Oat, grain, 184. 

hay, 191. 

straw, 185. 
Oil meal, 189. 
Oils, influence on milk fat, 276, 

drying and non-drying, 96. 

essential, 98. 

nature of, 98. 



J.32 



Agricultural Chemistry. 



Oleic acid, 96. 

Olein, 96. 

Oleomargarine, 285. 

Omasum. 220. 

Organic acids in plants, 99. 

Oxidation, 16. 

slow, 96. 
Oxen, ration for fattening, 258. 

ash stored up, 116. 

comparison with cow, 264. 
Oxygen, in the air, 29. 

occurrence, 7. 
Ozone, 31. 

Palinitiii, 96. 

Pancreatic juice, 223. 
Pace, influence on food require- 
ment, 256. 
Pasteurizing, 279. 
Paris green, 295. ^ 
Pears, 195. 
Peas, 188. 
Peat, 118. 
Pectins, 94. 
Pentosans, 94. 
Pentoses, 94. 
Pepsin, 222. 
Peptones, 207. 
Perspiration, 227. 
Petroleum emulsion, 305. 
Phosphates, loss by drainage, 66. 
Phosphatic fertilizers, 153. 
Phosphorus, function in plants, 
107. 

occurrence, 12. 

in animals, 210. 

in foods, 218. 
Phytin, 110. 
Pigs, ration for fattening, 260. 

rations for growing, 248. 

manure of, 113. 



Plants, assimilation, 86. 

constituents, 88. 

respiration, 87. 
Plums, 195. 
Pop corn, 186. 
Potash, loss in drainage, 66. 

fertilizers, 158. 
Potassium, function in plants, 106 

occurrence, 13. 
Potassium nitrate, 149. 
Potatoes, 195. 
Preservation of milk, 278. 
"Process" butter, 284. 
Proteins, classification, 100. 

kinds of, 101. 
Ptyalin, 219. 
Putrefaction, 17. 

Quartz, 36. 

Quick lime, 161. 

Hattiiiose, 91. 

Rain water, 69. 

Rape, 189. 

Rechnagel's phenomenon, 273. 

Reduction, 16. 

Reverted phosphates, 154. 

Rennin, 221. 

Rennet, 288. 

Renovated butter, 284. 

Resin soap, as insecticide, 306. 

Respiration, in animals, 226. 

in jilants, 87. 
Reticulum, 220. 
Rice, 186. 
Ripening, of cheese, 289. 

cream, 284. 
River water, 69. 
Rocks, classification of, 35. 
Root, crops, 193. 

pressure, 83. 



Index. 



338 



Rotation of crops, 203. 
Ruminants, digestion by, 231. 
Rye, 182. 

Salicylic acid, 279. 
Saliva, 219. 
Salt, common, 163. 
Sand, properties of, 45. 
Schweinfurth's green, 295. 
Sea water, 77. 

Season, influence on plant compo- 
sition, 198. 
Seeds, germination, 79. 
Sedimentary rocks, 35. 
Separated milk, 282. 
Sewage as manure, 75. 
Shales, 38. 
Sheep, nutritive ratio for, 262. 

digestion of foods, 231. 

manure, 113. 

production of wool, 261. 
Silage, corn, 192. 

clover, 192. 
Silicon, function in plants, 108. 

occurrence, 15. 
Silicates in soil, 37. 
Size of animal, influence on ration, 

254. 
Skimmed milk, 282. 
Soap, action on hard water, 70. 

nature of, 97. 
Sodium, occurrence, 13. 
Softening of hard water, 71. 
Soils, composition of, 61. 

definition of,, 35. 

fixation of nitrogen in, 44. 

formation, 40. 

gases in, 60. 

retention by, 55. 
Soil, sedentary and transported, 39. 

relation to heat, 48. 

relation to water, 52. 



tenacity of, 50. 

water in, 50. 

weight per acre, 61. 
Sorghum, 191. 
Specific heat, 48. 
Spontaneous combustion, 96. 
Starch, in plants, 91. 

influence on digestion, 233. 

part in nutrition, 217. 

productive value, 240. 
Steapsin, 223. 
Stems of plants, 83. 
Stearin, 96. 
Sterilization, 279. 
Stomata of plants, 85. 
Stomach, digestion in, 220. 
Straw as litter, 118. 

energy consumed in digestion 
of, 240. 
Sucrose, 90. 
Sugar beets, 194. 
Sugars, 90. 
Suint, 262. 

Sulphate of ammonia, 149. 
Sulphur, , function in plants, 107. 

occurrence, 11. 
Sulphur and lime wash, 302. 

dioxide, 34. 
Sunflower, 190. 
Super-phosphates, 154. 
Swedeycrop, 194. 
Sweet corn, 202. 

Teniperatvire of soils, 50. 

Terpenes, 98. 

Therms, 237. 

Thomas slag, 157. 

Tillage, 63. 

Timber, composition of, 179. 

Tobacco, 196. 

Transpiration from leaves, 81. 

Trees, food requirements, 195. 



334 



Ag7icuUnral Chemistry. 



Trypsin, 223. 

Tubercles on legumes, 29. 

Turnips, 194. 

I'rea, 227. 
Uric acid, 227. 
Urine, 227. 

Vetches, 171, 205. 

Warp soils, 76. 

Water, action of on lead, 72. 
action of on rocks, 41. 
hard, 70. 
mineral, 69. 
natural. 68. 
organic matter in, 73. 
physical properties of, 68. 
rain, 69. 
soft, 71. 
spring, 69. 
typical good and bad, 74. 



Waxes, 98. 

Wheat, 181. 

Wheat bran, 181. 

Wheat straw, 182. 

Whey, 291. 

White ants, 43. 

Wind, action on rocks, 42. 

Wolff's feeding standards, 235. 

Wood ashes, 160. 

Wool, production, 261. 

Woolen waste, 152. 

Work, production of, 255. 

Worms, in soil formation, 42. 

Xanthin, 213. 

Yolk, of wool, 262. 

Young animals, nutrition of, 248. 

Zein, 101. 

Zinc, in plants, 109. 



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